Implement ffa_mem_perm_get/set functions

Add functions for invoking FFA_MEM_PERM_GET and FFA_MEM_PERM_SET FF-A
1.1 interfaces. These calls can be used to query or change the access
rights of the memory regions of the SP. The patch includes tests and
mock implementations as well.

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: I9e29551768951f6cd58aa57d18d3b65ad8e4f441
7 files changed