serial: sc16is7xx: add missing support for rs485 devicetree properties

Retrieve rs485 devicetree properties on registration of sc16is7xx ports in
case they are attached to an rs485 transceiver.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
Link: https://lore.kernel.org/r/20230807214556.540627-7-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: hvilleneuvedoo

drivers/tty/serial/sc16is7xx.c

@@ -1554,6 +1554,10 @@ static int sc16is7xx_probe(struct device *dev,
 			goto out_ports;
 		}
 
+		ret = uart_get_rs485_mode(&s->p[i].port);
+		if (ret)
+			goto out_ports;
+
 		/* Disable all interrupts */
 		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_IER_REG, 0);
 		/* Disable TX/RX */