Added Microchip PolarFire SoC target, BSP framework, and CI/CD pipeline

[AmmarOkla12772]

Overview

This PR adds support for the Microchip PolarFire SoC Icicle Kit under targets/Microchip/POLARFIRE_ICICLE_RENODE/.

The goal is to provide a reusable 64-bit RISC-V ThreadX target and condition-monitoring demo running in Renode, while establishing a common BSP abstraction for future targets and automated build and simulation validation through GitHub Actions.

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Changes

• Added 64-bit RISC-V PolarFire SoC BSP with MMUART, CLINT timer, PLIC, trap handling, and board initialization
• Added multi-hart startup handling selecting Hart 1 (u54_1) for ThreadX execution and parking auxiliary application harts
• Added target-specific machine trap vector configuration and 10 ms ThreadX system timer interrupts
• Added a reusable BSP abstraction for board initialization, console output, and LED control
• Added PolarFire SoC board configuration for CPU clock, CLINT RTC frequency, and DRAM boundaries
• Added C runtime stubs for _write(), _sbrk(), and _exit()
• Added an industrial condition-monitoring demo using simulated LM75 temperature data
• Added producer-consumer communication using TX_QUEUE
• Added threshold-based alarm handling using TX_EVENT_FLAGS_GROUP
• Added virtual alarm LED control through the BSP abstraction
• Added periodic telemetry reporting over the BSP console
• Added automated Renode verification checking ThreadX boot, system tick progression, and overtemperature alarm output
• Added GitHub Actions CI pipeline covering ARM Cortex-M4 and 64-bit RISC-V targets
• Added pinned xPack RISC-V GCC toolchain configuration for reproducible CI builds
• Added the required Eclipse ThreadX MIT/SPDX license headers across the added source, header, assembly, script, and build files
• Updated target documentation with build, simulation, and automated test instructions

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Validation

Tested locally using Renode and the configured cross-compilation toolchains:

• PolarFire SoC target boots successfully in Renode
• ThreadX system tick advances consistently at 10 ms intervals
• ThreadX threads execute and context switching operates correctly
• Simulated LM75 temperature data is processed through the monitoring pipeline
• Overtemperature condition correctly triggers the alarm event flag and virtual LED
• Telemetry output remains stable over the MMUART console
• Headless Renode verification passes with expected ThreadX tick and alarm output
• ARM NUCLEO-F401RE target builds successfully through the CI pipeline
• PolarFire SoC 64-bit RISC-V target builds successfully through the CI pipeline
• No compilation errors or local test failures

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Toolchain

• Arm GNU Toolchain for NUCLEO-F401RE
• xPack RISC-V Embedded GCC 14.2.0
• CMake + Ninja build system
• Renode
• GitHub Actions

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Notes

The PolarFire target uses the reusable BSP interfaces for application-level hardware access, keeping the condition-monitoring application independent of platform-specific MMIO details. The CI pipeline provides automated build and headless Renode validation to detect build or runtime regressions.