Microchip PolarFire SoC BSP Bring-Up

[AmmarOkla12772]

Implement initial ThreadX support for the Microchip PolarFire SoC Icicle Kit (64-bit RISC-V configuration in Renode).

Goals:

• MPFS250T 64-bit multi-hart startup integration
• DRAM memory map & linker integration
• ThreadX scheduler bring-up (Hart 1 u54_1)
• Renode simulation platform integration
• build system integration
• example_build port contribution

DoD:

• Booting ThreadX on PolarFire SoC in Renode
• Baseline kernel scheduler validation
• Build documentation