scsi: ufs: wrap the i/o access operations

Simplify operations with hiding mmio_base.

Change-Id: If0df06647552cd67b8589c0bc9ec96ef6bc26018
Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Tested-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Santosh Y <santoshsy@gmail.com>
Patch-mainline: linux-scsi@vger.kernel.org @ 05/19/2013, 13:51
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Signed-off-by: Dolev Raviv <draviv@codeaurora.org>