Split platform.h into separate headers

Previously, platform.h contained many declarations and definitions
used for different purposes. This file has been split so that:

* Platform definitions used by common code that must be defined
  by the platform are now in platform_def.h. The exact include
  path is exported through $PLAT_INCLUDES in the platform makefile.

* Platform definitions specific to the FVP platform are now in
  /plat/fvp/fvp_def.h.

* Platform API declarations specific to the FVP platform are now
  in /plat/fvp/fvp_private.h.

* The remaining platform API declarations that must be ported by
  each platform are still in platform.h but this file has been
  moved to /include/plat/common since this can be shared by all
  platforms.

Change-Id: Ieb3bb22fbab3ee8027413c6b39a783534aee474a
diff --git a/Makefile b/Makefile
index 1069cd5..22f1fd6 100644
--- a/Makefile
+++ b/Makefile
@@ -160,9 +160,9 @@
 				-Iinclude/drivers/arm		\
 				-Iinclude/lib			\
 				-Iinclude/lib/aarch64		\
+				-Iinclude/plat/common		\
 				-Iinclude/stdlib		\
 				-Iinclude/stdlib/sys		\
-				-Iplat/${PLAT}			\
 				${PLAT_INCLUDES}		\
 				${SPD_INCLUDES}