Platform: Only put TF-M code to ER_TFM_CODE

The ER_TFM_CODE should only pick the real TF-M code,
rather than anything that does not match any pattern.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I13f8dba385c14fed06a4910d48859a25a0b5bd6f
diff --git a/toolchain_ARMCLANG.cmake b/toolchain_ARMCLANG.cmake
index 43bf595..97e1b4f 100644
--- a/toolchain_ARMCLANG.cmake
+++ b/toolchain_ARMCLANG.cmake
@@ -69,6 +69,8 @@
         --diag_suppress=6314
         # Duplicate input files
         --diag_suppress=6304
+        # Pattern only matches removed unused sections.
+        --diag_suppress=6329
         $<$<NOT:$<BOOL:${TFM_SYSTEM_FP}>>:--fpu=softvfp>
     )
 endmacro()