Implement PSCI_FEATURES API

This patch implements the PSCI_FEATURES function which is a mandatory
API in the PSCI 1.0 specification. A capability variable is
constructed during initialization by examining the plat_pm_ops and
spd_pm_ops exported by the platform and the Secure Payload Dispatcher.
This is used by the PSCI FEATURES function to determine which
PSCI APIs are supported by the platform.

Change-Id: I147ffc1bd5d90b469bd3cc4bbe0a20e95c247df7
diff --git a/services/std_svc/psci/psci_common.c b/services/std_svc/psci/psci_common.c
index 898a343..a31643e 100644
--- a/services/std_svc/psci/psci_common.c
+++ b/services/std_svc/psci/psci_common.c
@@ -558,7 +558,15 @@
  ******************************************************************************/
 void psci_register_spd_pm_hook(const spd_pm_ops_t *pm)
 {
+	assert(pm);
 	psci_spd_pm = pm;
+
+	if (pm->svc_migrate)
+		psci_caps |= define_psci_cap(PSCI_MIG_AARCH64);
+
+	if (pm->svc_migrate_info)
+		psci_caps |= define_psci_cap(PSCI_MIG_INFO_UP_CPU_AARCH64)
+				| define_psci_cap(PSCI_MIG_INFO_TYPE);
 }
 
 /*******************************************************************************