cmake: apply optimization flags to assembler

Commit 65471a6 separated
compiler flags into ASM, C and CXX as those flags may not be
universal to both assembler and compiler. Though, with that
separation, the assembler no longer gets the optimization
flags (e.g. speed/size optimizations). So adds this back so
the assembler can optimize the code if it chooses to. For
example, some instructions can be fused together to result
in small code.

Fixes #92439

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

Author: dcpleung

CMakeLists.txt

@@ -245,6 +245,7 @@ SOC_* symbol.")
 endif()
 
 # Apply the final optimization flag(s)
+zephyr_compile_options($<$<COMPILE_LANGUAGE:ASM>:${OPTIMIZATION_FLAG}>)
 zephyr_compile_options($<$<COMPILE_LANGUAGE:C>:${OPTIMIZATION_FLAG}>)
 zephyr_compile_options($<$<COMPILE_LANGUAGE:CXX>:${OPTIMIZATION_FLAG}>)