serial: msm_serial: add sparse context annotation

serial: msm_serial: add sparse context annotation

Add sparse context annotation to the receive handlers, which release and
reacquire the port lock, to silence sparse warnings:

	drivers/tty/serial/msm_serial.c:748:25: warning: context imbalance in 'msm_handle_rx_dm' - unexpected unlock
	drivers/tty/serial/msm_serial.c:814:28: warning: context imbalance in 'msm_handle_rx' - unexpected unlock

Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200723123327.5843-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>