mmc: sdhci: clear interrupt status during controller reset

In some cases, it is possible that the hardware might trigger
an interrupt just about the same time the software tries to
reset the controller. In such case, the hardware interrupt will
be handled after the current thread release spin lock. This leads
to spurious interrupt handling after the completion of reset.

Change-Id: I75211adee1179b0636a918f5ceb68a072ad02a6c
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>