mmc: dw_mmc: Handle DW_MCI_QUIRK_IDMAC_DTO properly

In (1fb5f68a mmc: dw_mmc: Don't loop when handling an interrupt), the
code for handling DW_MCI_QUIRK_IDMAC_DTO became dead code.  Move it to
where it ought to live.

Found by code inspection and compile-tested only--I don't know of any
boards that need DW_MCI_QUIRK_IDMAC_DTO.

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