Update on "[Executorch][llama] Enable quantized sdpa"

Enable leveraging quantized sdpa op when quantized kv cache is used. Instead of adding yet another arg, at the moment I have chosen to leverage quantize_kv_cache option.

Differential Revision: [D71833064](https://our.internmc.facebook.com/intern/diff/D71833064/)

[ghstack-poisoned]

Author: kimishpatel

extension/llm/custom_ops/CMakeLists.txt

@@ -21,7 +21,9 @@ if(NOT EXECUTORCH_ROOT)
 endif()
 
 set(_common_compile_options -Wno-deprecated-declarations -fPIC)
-list(APPEND _common_compile_options "-march=armv8.2-a+dotprod")
+if(CMAKE_SYSTEM_PROCESSOR MATCHES "arm64|aarch64")
+  list(APPEND _common_compile_options "-march=armv8.2-a+dotprod")
+endif()
 
 include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
 include(${EXECUTORCH_ROOT}/tools/cmake/Codegen.cmake)