Add minor fixes for FRI (#32)

* docs: Update references of Arm GNU Toolchain supported version

The project supports building with Arm Toolchain v13.2.Rel1.

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

* apps: Fix toolchain check in `CMakeLists.txt` files

Due to a syntax error, `CMAKE_C_COMPILER_ID` was incorrectly
compared to `ARMClang` in applications's main `CMakeLists.txt`.
Ensure the conditional statement uses `${CMAKE_C_COMPILER_ID}`
instead.

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

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Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>