ARM: SoC fixes for 6.2, part 3

The majority of bugfixes is once more for the NXP i.MX platform,
addressing issue with i.MX8M (UART, watchdog and ethernet) as well as
imx8dxl power button and the USB modem on an imx7 board. The reason that
i.MX always shows up here is obviously not that they are more buggy than
the others, but they have the most boards and are good about getting
fixes in quickly.

The other DT fixes are for the Nuvoton wpcm450 flash controller and
the i2c mux on an ASpeed board.

Lastly, there are updates to the MAINTAINERS entries for Mediatek,
AMD/Seattle and NXP SoCs, as well as a lone code fix for error
handling in the allwinner "rsb" bus driver.