RS-485 Overlay not working

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Hello.
I would like configure UART4 as RS-485.
But I have a problem with z dts file.

dts file: https://pastebin.com/raw/paGAsxUg
image: BeagleBoard.org Debian Image 2020-01-01

kernel: 4.14.108-ti-r124

driver: 8250 serial driver

please help.