ipmi: kcs: aspeed: Implement v2 bindings

The v2 bindings allow us to extract the resources from the devicetree.
The table in the driver is retained to derive the channel index, which
removes the need for kcs_chan property from the v1 bindings. The v2
bindings allow us to reduce the number of warnings generated by the
existing devicetree nodes.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Message-Id: <01ef3787e9ddaa9d87cfd55a2ac793053b5a69de.1576462051.git-series.andrew@aj.id.au>
Signed-off-by: Corey Minyard <cminyard@mvista.com>