ipmi: kcs: aspeed: Adapt to new LPC DTS layout

Add check against LPC device v2 compatible string to
ensure that the fixed device tree layout is adopted.
The LPC register offsets are also fixed accordingly.

Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Acked-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210319062752.145730-3-andrew@aj.id.au


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