ARM: dts: aspeed: tyan-s7106: Add uart_routing and fix vuart config

ARM: dts: aspeed: tyan-s7106: Add uart_routing and fix vuart config

Configure the vuart in such a way that it does not inhibit the SuperIO's
UART from functioning correctly. This allows the same DTS to be used for
both configurations with SuperIO and VUART (depending on the BIOS
build). The decision on whether to actually enable VUART can then be
made at runtime.

This change also enables the new uart_routing driver for the SuperIO
case.

Signed-off-by: Oskar Senft <osk@google.com>
Link: https://lore.kernel.org/r/20211130184855.1779353-1-osk@google.com
Signed-off-by: Joel Stanley <joel@jms.id.au>