misc: keba: Add UART devices

Add support for the UART auxiliary devices. This enables access to up to
3 different UARTs, which are implemented in the FPGA.

Signed-off-by: Gerhard Engleder <eg@keba.com>
Link: https://lore.kernel.org/r/20241011191257.19702-9-gerhard@engleder-embedded.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>