Update on "[Executorch] enable sleef consistently"

Earlier only android platofrms had support for sleef

Differential Revision: [D64571782](https://our.internmc.facebook.com/intern/diff/D64571782/)

[ghstack-poisoned]

Author: kimishpatel

shim/xplat/executorch/kernels/optimized/op_registration_util.bzl

@@ -98,7 +98,7 @@ def define_op_library(name, deps):
         deps = [
             "//executorch/runtime/kernel:kernel_includes",
         ] + augmented_deps,
-        fbandroid_platform_preprocessor_flags = get_vec_android_preprocessor_flags(),
+        preprocessor_flags = get_vec_preprocessor_flags(),
         # sleef needs to be added as a direct dependency of the operator target when building for Android,
         # or a linker error may occur. Not sure why this happens; it seems that fbandroid_platform_deps of
         # dependencies are not transitive