Include `plat_psci_common.c` from the new location

The `plat_psci_common.c` was moved to the new location `plat/common`
and a stub file was retained at previous location for compatibility. This
patch modifies the platform makefiles to include the file from the new
location.

Change-Id: Iabddeeb824e9a5d72d176d7c644735966c8c0699
diff --git a/plat/nvidia/tegra/common/tegra_common.mk b/plat/nvidia/tegra/common/tegra_common.mk
index 2ecf5f5..03ca773 100644
--- a/plat/nvidia/tegra/common/tegra_common.mk
+++ b/plat/nvidia/tegra/common/tegra_common.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
@@ -52,7 +52,7 @@
 				drivers/delay_timer/delay_timer.c		\
 				drivers/ti/uart/16550_console.S			\
 				plat/common/aarch64/platform_mp_stack.S		\
-				plat/common/aarch64/plat_psci_common.c		\
+				plat/common/plat_psci_common.c			\
 				${COMMON_DIR}/aarch64/tegra_helpers.S		\
 				${COMMON_DIR}/drivers/memctrl/memctrl.c		\
 				${COMMON_DIR}/drivers/pmc/pmc.c			\