Implement ARM Standard Service

This patch implements ARM Standard Service as a runtime service and adds
support for call count, UID and revision information SMCs. The existing
PSCI implementation is subsumed by the Standard Service calls and all
PSCI calls are therefore dispatched by the Standard Service to the PSCI
handler.

At present, PSCI is the only specification under Standard Service. Thus
call count returns the number of PSCI calls implemented. As this is the
initial implementation, a revision number of 0.1 is returned for call
revision.

Fixes ARM-software/tf-issues#62

Change-Id: I6d4273f72ad6502636efa0f872e288b191a64bc1
diff --git a/include/psci.h b/include/psci.h
index 922f95f..6fe1d8a 100644
--- a/include/psci.h
+++ b/include/psci.h
@@ -47,9 +47,15 @@
 #define PSCI_MIG_INFO_TYPE		0x84000006
 #define PSCI_MIG_INFO_UP_CPU_AARCH32	0x84000007
 #define PSCI_MIG_INFO_UP_CPU_AARCH64	0xc4000007
-#define PSCI_SYSTEM_OFF		0x84000008
+#define PSCI_SYSTEM_OFF			0x84000008
 #define PSCI_SYSTEM_RESET		0x84000009
 
+/*
+ * Number of PSCI calls (above) implemented. System off and reset aren't
+ * implemented as yet
+ */
+#define PSCI_NUM_CALLS			13
+
 /*******************************************************************************
  * PSCI Migrate and friends
  ******************************************************************************/