mtd: ep93xx: cleanup includes in ts7250 nand driver

1. <linux/io.h> should be included not <asm/io.h>
2. add platform specific header <mach/ts72xx.h>

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>