dt-bindings: ipmi: Add optional SerIRQ property to ASPEED KCS devices

dt-bindings: ipmi: Add optional SerIRQ property to ASPEED KCS devices

Allocating IO and IRQ resources to LPC devices is in-theory an operation
for the host, however ASPEED don't appear to expose this capability
outside the BMC (e.g. SuperIO). Instead, we are left with BMC-internal
registers for managing these resources, so introduce a devicetree
property for KCS devices to describe SerIRQ properties.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Rob Herring <robh@kernel.org>
Message-Id: <20210608104757.582199-14-andrew@aj.id.au>
Signed-off-by: Corey Minyard <cminyard@mvista.com>