Ensure same flags are used for both GCC and ARMClang

Change-Id: Ib37930e7efb0663e9c39bb6c39af8cc62cf3f37c
diff --git a/cmake/toolchain/armclang.cmake b/cmake/toolchain/armclang.cmake
index 25c510c..257c2a8 100644
--- a/cmake/toolchain/armclang.cmake
+++ b/cmake/toolchain/armclang.cmake
@@ -84,6 +84,7 @@
     -Wnull-dereference
     -Wno-format-extra-args
     -Wno-unused-function
+    -Wno-unused-parameter
     -Wno-unused-label
     -Wno-missing-field-initializers
     -Wno-return-type)