serial: 8250_aspeed_vuart: add aspeed, lpc-io-reg and aspeed, lpc-interrupts DT properties

These allow describing all the Aspeed VUART attributes currently
available via sysfs.  aspeed,lpc-interrupts provides a replacement for
the deprecated aspeed,sirq-polarity-sense property.

Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210412034712.16778-4-zev@bewilderbeest.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>