PSCI: Do psci_setup() as part of std_svc_setup()

This patch moves the invocation of `psci_setup()` from BL31 and SP_MIN
into `std_svc_setup()` as part of ARM Standard Service initialization.
This allows us to consolidate ARM Standard Service initializations which
will be added to in the future. A new function `get_arm_std_svc_args()`
is introduced to get arguments corresponding to each standard service.
This function must be implemented by the EL3 Runtime Firmware and both
SP_MIN and BL31 implement it.

Change-Id: I38e1b644f797fa4089b20574bd4a10f0419de184
diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index 7b0b675..fae5ee4 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -53,21 +53,27 @@
  ******************************************************************************/
 static uint32_t next_image_type = NON_SECURE;
 
+/*
+ * Implement the ARM Standard Service function to get arguments for a
+ * particular service.
+ */
+uintptr_t get_arm_std_svc_args(unsigned int svc_mask)
+{
+	/* Setup the arguments for PSCI Library */
+	DEFINE_STATIC_PSCI_LIB_ARGS_V1(psci_args, bl31_warm_entrypoint);
+
+	/* PSCI is the only ARM Standard Service implemented */
+	assert(svc_mask == PSCI_FID_MASK);
+
+	return (uintptr_t)&psci_args;
+}
+
 /*******************************************************************************
  * Simple function to initialise all BL31 helper libraries.
  ******************************************************************************/
 void bl31_lib_init(void)
 {
-	/* Setup the arguments for PSCI Library */
-	DEFINE_STATIC_PSCI_LIB_ARGS_V1(psci_args, bl31_warm_entrypoint);
-
 	cm_init();
-
-	/*
-	 * Initialize the PSCI library here. This also does EL3 architectural
-	 * setup.
-	 */
-	psci_setup(&psci_args);
 }
 
 /*******************************************************************************
@@ -89,7 +95,7 @@
 	/* Initialise helper libraries */
 	bl31_lib_init();
 
-	/* Initialize the runtime services e.g. psci */
+	/* Initialize the runtime services e.g. psci. */
 	INFO("BL31: Initializing runtime services\n");
 	runtime_svc_init();