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: Icd22f318d6f24e54afbcedacf026977b29de4e95
Signed-off-by: Sarthak Garg <sartgarg@codeaurora.org>