mmc: sdhci: Force crash upon emmc unexpected interrupt

If mmc driver encounters unexpected interrupt, implies that the s/w
state machine and h/w state machine went out of sync. And it usually
results in continuous logging and leads to watchdog bite.

Due to continuous logging, we lose the actual info that leads to this
unexpected interrupt. So force crash upon mmc driver encounters this
unexpected error.

Change-Id: Ia39dd84b471049f91d0cc4d6cdb7562199cce860
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>