[TF-M] tfm_ns_interface functions refactoring

Hi,

I made some changes to the tfm_ns_interface_ functions. They have common implementations that call os_wrapper_ functions. With these changes, RTOSes only need to implement the OS dependent functions defined in os_wrappers rather than the tfm_ns_interface_ functions.

There are several changes with a same topic: https://review.trustedfirmware.org/q/topic:%22refine_ns_interface_functions%...) Please help on reviewing. Thanks.

- Kevin