[BUG] The file flash-dtcm.ld is missing in NuttX master and all previous versions.

### Description / Steps to reproduce the issue

**flash-dtcm.ld** file missing

boards/arm/imxrt/imxrt1020-evk/Make.defs

https://github.com/apache/nuttx/blob/1bfe705226788512bf17aa00b3fce05469fd11fb/boards/arm/imxrt/imxrt1020-evk/scripts/Make.defs#L28

boards/arm/imxrt/imxrt1050-evk/scripts/Make.defs

https://github.com/apache/nuttx/blob/1bfe705226788512bf17aa00b3fce05469fd11fb/boards/arm/imxrt/imxrt1050-evk/scripts/Make.defs#L28

boards/arm/imxrt/arcx-socket-grid/scripts/Make.defs

https://github.com/apache/nuttx/blob/1bfe705226788512bf17aa00b3fce05469fd11fb/boards/arm/imxrt/arcx-socket-grid/scripts/Make.defs#L28
```
ifeq ($(CONFIG_ARMV7M_DTCM),y)
LDSCRIPT = flash-dtcm.ld
else
LDSCRIPT = flash-ocram.ld
endif
```

### On which OS does this issue occur?

[OS: BSD], [OS: Linux], [OS: Mac], [OS: Windows]

### What is the version of your OS?

GitHub Actions

### NuttX Version

master and all old versions (9.0-12.10)

### Issue Architecture

[Arch: arm]

### Issue Area

[Area: Build System]

### Host information

_No response_

### Verification

- [x] I have verified before submitting the report.

Start with the referenced boards/arm/imxrt/imxrt1020-evk/Make.defs, boards/arm/imxrt/imxrt1050-evk/scripts/Make.defs, and boards/arm/imxrt/arcx-socket-grid/scripts/Make.defs. Trace the CONFIG_ARMV7M_DTCM linker-script selection and verify that builds using it can find flash-dtcm.ld; done means the missing-file reference is resolved for the affected boards.

Written by the indexing model from the issue text.