TIClang: Make ARM architecture id uppercase

The initial compiler support implemented in commit 9ba0a54554 (TIClang:
Add support for TI Clang-based compilers, including tiarmclang,
2023-12-06) introduced `Arm` as architecture instead of `ARM` which is
used for all other compilers.

Modules/CMakePlatformId.h.in

@@ -221,7 +221,7 @@
 
 #elif defined(__clang__) && defined(__ti__)
 # if defined(__ARM_ARCH)
-#  define ARCHITECTURE_ID "Arm"
+#  define ARCHITECTURE_ID "ARM"
 
 # else /* unknown architecture */
 #  define ARCHITECTURE_ID ""