Add SolidRun LX2160A CEX7 (HoneyComb LX2K) board support

[lizthegrey]

Summary

I have a working set of patches adding SolidRun LX2160A CEX7 (HoneyComb LX2K) board support to edk2-platforms, rebased onto current upstream master. I'd like to gauge interest before submitting a PR.

What's included

• ~640 SolidRun/NXP hardware support files (DPAA2 Ethernet, SPI, MMC, SMBIOS, ACPI tables, I2C)
• Board DSC/FDF for the LX2160aCex7 platform
• StandaloneMm DSC for OP-TEE-backed Secure Boot variable storage
• Tested on real hardware (SolidRun HoneyComb LX2K) with ATF v2.12, OP-TEE 4.9.0, edk2-stable202602
• Boots to Ubuntu 24.04 with UEFI Secure Boot (Microsoft keys enrolled)
• CPU overclock support (2200 MHz / 3200 MT/s DDR)

Current state

The patches are structured as:

1. 640 SolidRun-only files (no overlap with existing upstream content)
2. 18 files that overlap with existing upstream NXP Chassis/Silicon code (merged with minimal diff)
3. Build fixes for API compatibility with current upstream (SwapMmio removal, SocGetClock signature changes, etc.)
4. Secure Boot support (StandaloneMm DSC, FD size increase, OP-TEE MM communication driver linkage)

The complete patch set is at: https://github.com/lizthegrey/edk2-platforms/tree/lizf.upstream-rebase (17 commits on upstream/master)

Writeup with full details: https://gist.github.com/lizthegrey/9344dc71dc4ac11f9d6c79d7c143e535

Questions

1. Would SolidRun LX2160A board support be welcome in edk2-platforms?
2. The NXP LX2160A Silicon/Chassis code already exists upstream but is incomplete — should I submit the SolidRun board package as a Platform/SolidRun/ directory, or is there a preferred structure?
3. The 18 overlapping files touch shared NXP infrastructure (Chassis3V2, DPAA2 libraries). Should these be separate PRs from the board-specific files?