Make enablement of the MMU more flexible

This patch adds a 'flags' parameter to each exception level specific function
responsible for enabling the MMU. At present only a single flag which indicates
whether the data cache should also be enabled is implemented. Subsequent patches
will use this flag when enabling the MMU in the warm boot paths.

Change-Id: I0eafae1e678c9ecc604e680851093f1680e9cefa
diff --git a/services/std_svc/psci/psci_afflvl_on.c b/services/std_svc/psci/psci_afflvl_on.c
index d620172..1551cfe 100644
--- a/services/std_svc/psci/psci_afflvl_on.c
+++ b/services/std_svc/psci/psci_afflvl_on.c
@@ -361,7 +361,7 @@
 	/*
 	 * Arch. management: Turn on mmu & restore architectural state
 	 */
-	bl31_plat_enable_mmu();
+	bl31_plat_enable_mmu(0);
 
 	/*
 	 * All the platform specific actions for turning this cpu