imx: Move some header files from arch-mxs to imx-common

The following headers are moved to a i.MX common location:

- regs-common.h
- regs-apbh.h
- regs-bch.h
- regs-gpmi.h
- dma.h

This way this header can be re-used also by other i.MX platforms.
For example the i.MX6 which will need it for the upcoming NAND
support.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/drivers/mtd/nand/mxs_nand.c b/drivers/mtd/nand/mxs_nand.c
index e38e151..c21fd69 100644
--- a/drivers/mtd/nand/mxs_nand.c
+++ b/drivers/mtd/nand/mxs_nand.c
@@ -34,8 +34,10 @@
 #include <asm/io.h>
 #include <asm/arch/clock.h>
 #include <asm/arch/imx-regs.h>
+#include <asm/imx-common/regs-bch.h>
+#include <asm/imx-common/regs-gpmi.h>
 #include <asm/arch/sys_proto.h>
-#include <asm/arch/dma.h>
+#include <asm/imx-common/dma.h>
 
 #define	MXS_NAND_DMA_DESCRIPTOR_COUNT		4