ARM: config: aspeed: Enable KCS adapter for raw SerIO

Raw SerIO is used by the OpenBMC debug-trigger application to take
signals from the host that applications are unresponsive on the BMC.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20210819065203.2620911-3-joel@jms.id.au


Signed-off-by: Joel Stanley <joel@jms.id.au>