mmc: omap: handle controller errors properly

mmc: omap: handle controller errors properly

According to OMAP3 TRM, when the controller reports certain errors,
driver must perform a software reset. This is done by setting a bit
in SYSCTL and waiting it to clear:
- SRC on command timeout (CTO)
- SRD on data errors (DTO, DCRC and DEB)

This fixes a problem seen on OMAP3 pandora board with some cards
that won't work with a message printed multiple times:
  timedout waiting on cmd inhibit to clear

Code loosely based on Linux omap_hsmmc driver.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>