msm_serial_hs_lite: Increase Rx FIFO Watermark and AUTO RFR Value

UARTDM Core is having 64 words of Tx FIFO and 64 words of Rx FIFO.
Currently RFWR (Receive FIFO Watermark) and AUTO RFR values are
programmed as 12 words (i.e. 48 bytes). For better performance,
increase RFWR and AUTO RFR values from 12 words to 48 words
(i.e. 192 bytes).

Change-Id: Ib5a8570d2382c3047e4581acb349f72911bc6de5
Signed-off-by: Mayank Rana <mrana@codeaurora.org>