serial: msm_geni_serial: Do not check_transfers_inflight() post port_close

When port is closed, Currently driver calls wait_for_transfers_inflight()
function to check for pending transfers. During this
check_transfers_inflight operation their a possibility to see
RX line data in DMA_RX_LENGTH_IN register counter and can lead
to introduce additional delays during shutdown.

This patch checking for RX_ACTIVE state. If RX is active then
only wait for transfers_inflight.

Change-Id: I2b0647ce64d8c24e0161d07dd761fa9671defded
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>