SPM: Support blocking calls

Note that the arguments passed during the SMC call don't comply with the
SPCI specifications. This will be fixed in following patches, but it is
needed to implement a few more SPCI SMCs to be able to do it. The
current code allows us to start testing it.

Change-Id: Ief0e75d072b311737fcdb0c6a60ba5b7406a9ee5
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
5 files changed