ARM: OMAP: Split sram.h to local headers and minimal shared header

Most of the defines are specific to omap1 and omap2+,
and should be in the local headers. Only minimal function
prototypes need to be shared.

As discussed on linux-arm-kernel, we want to avoid
relative includes for the arch/arm/*omap* shared code:

http://www.spinics.net/lists/linux-omap/msg80520.html

So this patch re-adds a minimal plat/sram.h.

The new plat/sram.h must not be included from drivers,
that will break build for omap2+ CONFIG_MULTIPLATFORM.

Note that this patch temporarily adds two more
relative includes; Those will be removed in the
following patch.

Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
index 4fadc78..814f699 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -27,8 +27,6 @@
 
 #include <plat-omap/dma-omap.h>
 
-#include "../plat-omap/sram.h"
-
 #include "omap_hwmod.h"
 #include "soc.h"
 #include "iomap.h"
@@ -43,6 +41,7 @@
 #include "omap-pm.h"
 #include "sdrc.h"
 #include "serial.h"
+#include "sram.h"
 
 /*
  * The machine specific code may provide the extra mapping besides the