msm_serial_hs: Ensure RX side disable completes during port close

The wakeup sequnce can alter the flush state resulting in a indefinite
wait on closing RX side of the port. Fix this by using wait_event_timeout
and disabling the RFR line.

Change-Id: I6abc2565aa08fcc04394a840ef37f62a39617b0f
Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>