mmc: dw_mmc: correct mishandling error interrupt

Datasheet of SYNOPSYS mentions that DTO(Data Transfer Over) interrupt
will be raised even if some error interrupts, however it is actually
found that DTO does not occur. SYNOPSYS has confirmed this issue.
Current implementation defers the call of tasklet_schedule until DTO
when the error interrupts is happened. This patch fixes error handling.

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