msm_serial_hs: Add support to handle Rx BREAK condition

Currently Rx Break Error condition is not checked using UART_DM_SR
register. Hence by default null-character is being inserted on
receiving Rx Error or Rx Break condition. Application sets termios
c_iflag if it needs any notification related to any Rx Error or
Break condition. Hence add support to handle Rx Break condition and
insert null-character conditionally based on termios.c_iflag.

CRs-Fixed: 412201
Change-Id: I7f496e42757b949f597d5dbe5c1f1ca88ee53c8c
Signed-off-by: Mayank Rana <mrana@codeaurora.org>