tty: serial: imx: disable the break condition when shutdown the uart port

The comment in imx_uart_shutdown() says to disable the break condition,
but it doesn't actually do that, here fix this by disabling UCR1_SNDBRK
when closing the uart port like other uart drivers do.

Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20221214031137.28815-4-sherry.sun@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>