mmc: dw_mmc: Set timeout to max upon resume

The TMOUT register is set to 0xffffffff at probe time but isn't
set after suspend/resume.  Add an init of this value.

No problems were observed without this (it will also be set in
__dw_mci_start_request if there is data to send), but it makes the
register dump before and after suspend cleaner.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>