mmc: msm_sdcc: Fix wrong update of transfer remain variable

The value returned by the msmsdcc_pio_read() will be a 32bit
aligned value, which could be more than what we have requested
to read due to alignment force. Make sure that
host->curr.xfer_remain is updated with correct value.

Change-Id: I8fe1ec7b51626c53d39fe392122f357a3a8db8e2
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>