mmc: dw_mmc: modify quirks bit-shift control

If we need some quirks, maybe add quirks in future
But now, quirks value set to integer..later we should be confused..
So I think that need bit-shift control.

And If we need not any quirks, we didn't set anything..
(Need not DW_MCI_QUIRK_NONE)

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>