ipmi: kcs: aspeed: Remove old bindings support

It's been a few releases since we depreciated the "v1" bindings. Remove
support from the driver as all known device trees have been updated to
use the new bindings.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Message-Id: <20220228062840.449215-1-joel@jms.id.au>
Signed-off-by: Corey Minyard <cminyard@mvista.com>