PSYS DKMS module permanently defers on kernel 7.0-rc7 (in-tree ISYS)

## Summary

The PSYS DKMS module from `intel-ipu7-dkms-git` permanently defers probe when used alongside the **in-tree** IPU7 ISYS driver on kernel 7.0-rc7. This means the hardware ISP is unusable, forcing users to fall back to libcamera's software ISP (~65% CPU, poor image quality).

## Environment

- Dell XPS with Intel Panther Lake
- CachyOS, kernel 7.0.0-rc7-2-cachyos-rc (IPU7 ISYS is in-tree)
- Sensor: OV08X40 (OVTI08F4)
- Bridge: Synaptics SVP7500 USBIO
- AUR packages: intel-ipu7-camera-bin, intel-ipu7-dkms-git, intel-ipu7-camera-hal-git

## Problem

The DKMS PSYS module checks `adev->isp->ipu7_bus_ready_to_probe` in `ipu-psys.c` (line ~1345). While this field **does** exist in the in-tree `struct ipu7_device` and **is** set to `true` at the end of successful probe in `ipu7.c`, PSYS appears to probe before the parent driver completes, seeing the flag as `false` and returning `-EPROBE_DEFER`.

Attempting to patch out the check (`if (0)` instead of `if (!adev->isp->ipu7_bus_ready_to_probe)`) results in a kernel crash (SIGKILL), suggesting deeper ABI/structural incompatibilities between the DKMS PSYS module and the in-tree ISYS driver.

## dmesg output

```
intel_ipu7_psys: probe of intel_ipu7_psys.0 deferred
# Never resolves - permanently deferred
```

## Current workaround

Blacklist PSYS and use libcamera's software ISP:
```
# /etc/modprobe.d/ipu7-usbio-order.conf
blacklist intel_ipu7_psys
```

Then relay through GStreamer + v4l2loopback for browser compatibility.

## Request

Could you provide guidance on:
1. Whether the DKMS PSYS module is expected to work with the in-tree 7.0-rc7 ISYS driver?
2. If not, what kernel version / driver combination is required for PSYS to work?
3. Whether there are plans to upstream PSYS to the mainline kernel?

## Full guide

I've documented the complete workaround (software ISP path) for others hitting this issue:
https://www.reddit.com/r/cachyos/ (search for "IPU7 camera guide")

Start with the probe-order check in ipu-psys.c around line 1345, then compare the in-tree ISYS definitions and probe completion in ipu7.c. Reproduce the permanent -EPROBE_DEFER from the provided dmesg output and investigate the crash when the check is bypassed. Done means documenting a supported kernel/driver combination or the incompatibility and upstream status.

Written by the indexing model from the issue text.