TPS68470 missing board-data for Dell Latitude 7320 Detachable (IPU6, OV8856)

## System Information
- **Model:** Dell Latitude 7320 Detachable
- **DMI system-product-name:** Latitude 7320 Detachable
- **DMI baseboard-product-name:** 0TNW0H
- **BIOS version:** 1.45.0
- **Manufacturer:** Dell Inc.
- **OS:** Ubuntu 26.04 (resolute)
- **Kernel:** 7.0.0-22-generic
- **Camera Sensor:** OmniVision OV8856 (ACPI: OVTI8856:00)
- **Power Controller:** TPS68470 (ACPI: INT3472:07), REVID 0x21
- **IPU:** Intel IPU6 (Device 0x9a19), PCI 0000:00:05.0

## Problem

Camera does not work. The IPU6 driver correctly detects the connected sensor:

> [ 4.234092] intel-ipu6 0000:00:05.0: Found supported sensor OVTI8856:00
> [ 4.234180] intel-ipu6 0000:00:05.0: Connected 1 cameras
> [ 4.239303] intel-ipu6 0000:00:05.0: Sending BOOT_LOAD to CSE
> [ 4.248666] intel-ipu6 0000:00:05.0: Sending AUTHENTICATE_RUN to CSE
> [ 4.320510] intel-ipu6 0000:00:05.0: CSE authenticate_run done
> [ 4.320521] intel-ipu6 0000:00:05.0: IPU6-v0[9a19] hardware version 1

However, the TPS68470 PMIC fails to find board-data for this model, so the sensor never receives power:

> [ 4.700093] int3472-tps68470 i2c-INT3472:07: TPS68470 REVID: 0x21
> [ 4.700260] int3472-tps68470 i2c-INT3472:07: error -ENODEV: No board-data found for this model

As a result:
- The OV8856 never appears on the I2C bus (`ls /sys/bus/i2c/devices/` shows nothing for it)
- `media-ctl -p` shows the IPU6 CSI2 receivers with unconnected `SINK,MUST_CONNECT` pads — no sensor entity is present in the graph
- `cam -l` (libcamera-tools) reports "No sensor found for /dev/media0"

## What I've already ruled out
- `ov8856` kernel module is loaded successfully (`lsmod` confirms it, `ipu_bridge` and `v4l2_async`/`v4l2_fwnode` all load without error)
- `intel-ipu6-dkms` is installed and working at the IPU/CSE level
- This is not a Secure Boot / lockdown issue — I disabled Secure Boot and the failure is unchanged; it happens purely at PMIC board-data lookup
- Dynamic debug confirms the driver returns -ENODEV immediately on DMI board-data lookup, before reaching any GPIO/regulator mapping code — so there's nothing for me to introspect at runtime; the wiring info needs to be added as a static board_data entry, similar to the existing Dell Latitude 7212 Rugged Extreme Tablet entry.

## Request

Could someone with access to a Dell Latitude 7320 Detachable reference design (or contacts at Dell) help identify and add the correct TPS68470 board-data entry (regulator rail mapping for avdd/dvdd/dovdd, and GPIO pin assignment for reset/powerdown/clock-enable) for this model? Happy to test any proposed patch on the actual hardware and report back with dmesg / media-ctl output.

I attempted to extract the DSDT myself for cross-referencing, but ran into a recurring `iasl` disassembly issue (`Unterminated quoted string`, `Maximum error count (200) exceeded`) that prevented producing a usable `.dsl` file. Happy to provide the raw `dsdt.dat`/ACPI table dump if that's useful to a maintainer who can work around the iasl issue, or any other diagnostics needed.

[dsdt-latitude7320.dat.gz](https://github.com/user-attachments/files/29182341/dsdt-latitude7320.dat.gz)

## Hardware reference (similar known-working entries for comparison)
This appears analogous to previously-reported cases:
- intel/ipu6-drivers#414 (MSI Prestige 14 AI+ Evo, OV5675, same "No board-data found" failure mode)
- Launchpad bug 2121826 (Dell Latitude 5290 2-in-1, same failure mode, resolved by reusing the Dell Latitude 7212 Rugged Extreme Tablet board-data entry)

Read the existing Dell Latitude 7212 Rugged Extreme Tablet board-data entry and inspect the attached dsdt-latitude7320.dat.gz for comparable ACPI and hardware details. Done means the Latitude 7320 Detachable has TPS68470 board-data, the -ENODEV lookup error is gone, and the OV8856 appears on I2C and in the media graph.

Written by the indexing model from the issue text.