arch: arm: Separate common kernel_arch_func code

This commit separates kernel_arch_func.h into two header file,
'cortex_a_r/kernel_arch_func.h' and 'cortex_m/kernel_arch_func.h', it
also removes some functions which is empty.

Signed-off-by: Huifeng Zhang <Huifeng.Zhang@arm.com>
6 files changed