mmc: host: sdhci-msm: Enable SDHC FIFO explicitly

Enable SDHC FIFO explicitly by disabling the alternative FIFO.

The boot-loaders might use alternative FIFO instead of HC FIFO.
And the vendor specific register which has this setting won't get
reset with controller reset. So the FIFO setting done by the
bootloader would remain as it is unless its explicitly cleared.
Without clearing this setting, mmc driver can't make use of regular
FIFO mode.

Change-Id: I8c7ff9b20c33518fb9013cce2f9284117fc2ce3c
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>