ARM: OMAP2+: gpmc: localize gpmc header

Requirement of gpmc header outside of mach-omap2 has been
cutoff, move gpmc header file in plat-omap folder to local
mach-omap2 folder

Objective - common zImage participation of omap

Signed-off-by: Afzal Mohammed <afzal@ti.com>

arch/arm/mach-omap2/board-rx51.c

@@ -25,7 +25,7 @@
 
 #include "common.h"
 #include <plat/dma.h>
-#include <plat/gpmc.h>
+#include "gpmc.h"
 #include <plat/usb.h>
 
 #include "mux.h"