mmc: tmio_mmc: fix CMD irq handling

With current code card insert/eject interrupts will acknowledge outstanding
commands. Normally this seems to be no problem, however if the hardware gets
stuck and no interrupts for CMD_TIMEOUT or CMD_RESPEND are generated, then
inserting and ejecting cards will falsely acknowledge outstanding commands
from the core.

This patch changes the behavior so that CMDs are only acked, if
CMD_TIMEOUT or CMD_RESPEND is received.

Signed-off-by: Arnd Hannemann <arnd@arndnet.de>
Signed-off-by: Chris Ball <cjb@laptop.org>