Removing change to bzl file since PAL can't and should not be built in a non-zephyr environment

Author: BujSet

runtime/platform/targets.bzl

@@ -45,7 +45,6 @@ def define_common_targets():
             "ovr_config//os:android": ["default/android.cpp"],
             "DEFAULT": _select_pal({
                 "minimal": ["default/minimal.cpp"],
-                "arm_zephyr": ["default/arm_zephyr.hpp"],
                 "posix": ["default/posix.cpp"],
         })}),
         deps = [