serial: imx: Remove serial_rs485 sanitization

The driver provides different rs485_supported for the case where RTS is
not available making it unnecessary to handle it in
imx_uart_rs485_config.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-32-ilpo.jarvinen@linux.intel.com


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