Remove the use of global own_id from ffarpc_caller

Pass own_id as the parameter of ffa_caller_init to remove dependency
on own_id global variable. Change service locator to query the caller's
id via sp_discovery_own_id_get and pass it to the ffarpc_caller_init.

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: I1f654441f9a4f777335c111ac278aeeebd75bf30
7 files changed