feat(psci): add psci_do_manage_extensions API

Adding a new API under PSCI library,for managing all the architectural
features, required during power off or suspend cases.

Change-Id: I1659560daa43b9344dd0cc0d9b311129b4e9a9c7
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
diff --git a/lib/psci/psci_common.c b/lib/psci/psci_common.c
index f9de432..1333b1a 100644
--- a/lib/psci/psci_common.c
+++ b/lib/psci/psci_common.c
@@ -1164,6 +1164,8 @@
  ******************************************************************************/
 void psci_pwrdown_cpu(unsigned int power_level)
 {
+	psci_do_manage_extensions();
+
 #if HW_ASSISTED_COHERENCY
 	/*
 	 * With hardware-assisted coherency, the CPU drivers only initiate the
@@ -1283,3 +1285,13 @@
 
 	return true;
 }
+
+/*******************************************************************************
+ * This function performs architectural feature specific management.
+ * It ensures the architectural features are disabled during cpu
+ * power off/suspend operations.
+ ******************************************************************************/
+void psci_do_manage_extensions(void)
+{
+
+}