serial: sc16is7xx: add missing support for rs485 devicetree properties

Hi, the following patch:

b4a778303ea0 serial: sc16is7xx: add missing support for rs485 devicetree properties

Was introduced in kernel 6.5.

Without it, the rs485 devicetree properties are not applied and the RS-485 ports do not work.

I would like it to be applied to the stable kernel 6.1.

It applies cleanly and was tested on this kernel using a custom board with a Variscite IMX8MN NANO SOM, a NewHaven LCD, and two SC16IS752 on a SPI bus. The four UARTs are using RS-485 mode.

Thank you, Hugo Villeneuve