cmake: using zephyr_get_compile_options_for_lang_as_string()

With the distinction between zephyr_get_compile_options_for_lang() and
zephyr_get_compile_options_for_lang_as_string() regarding list handling
and thus quoting, then zephyr_get_compile_options_for_lang_as_string()
is now used for CMake source file properties for compilation of
kobject_hash.c source file.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

CMakeLists.txt

@@ -754,7 +754,7 @@ if(CONFIG_CODE_DATA_RELOCATION)
 endif()
 
 if(CONFIG_USERSPACE)
-  zephyr_get_compile_options_for_lang(C compiler_flags_priv)
+  zephyr_get_compile_options_for_lang_as_string(C compiler_flags_priv)
   string(REPLACE "$<TARGET_PROPERTY:compiler,coverage>" ""
          NO_COVERAGE_FLAGS "${compiler_flags_priv}"
   )