serial: ar933x: Remove superfluous code in ar933x_config_rs485()

In ar933x_config_rs485() the check for the RTS GPIO is not needed since in
case the GPIO is not available at driver init ar933x_no_rs485 is assigned
to port->rs485_supported and this function is never called. So remove the
check.

Also in uart_set_rs485_config() the serial core already assigns the passed
serial_rs485 struct to the uart port. So remove the assignment in the
drivers rs485_config() function to avoid redundancy.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20220710164442.2958979-3-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>