spmd: add FFA_INTERRUPT forwarding

In the case of a SP pre-empted by a non-secure interrupt, the SPMC
returns to the SPMD through the FFA_INTERRUPT ABI. It is then forwarded
to the normal world driver hinting the SP has to be resumed after the
non-secure interrupt has been serviced.
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I51a694dddcb8ea30fa84e1f11d018bc2abec0a56

services/std_svc/spmd/spmd_main.c

@@ -639,7 +639,7 @@ uint64_t spmd_smc_handler(uint32_t smc_fid,
 		}
 
 		/* Fall through to forward the call to the other world */
-
+	case FFA_INTERRUPT:
 	case FFA_MSG_YIELD:
 		/* This interface must be invoked only by the Secure world */
 		if (!secure_origin) {