refactor(spm): `ffa_memory_access` constructors

Add `ffa_memory_access_init_permissions` and
`ffa_memory_access_init_permissions_from_mem_func` helpers.

Change-Id: I9a5bb09e7f230a65decff7f58a0c188aff3e7449
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
4 files changed