ARM: dts: aspeed: rainier: Add IBM Operation Panel I2C device

Set I2C bus 7 to multi-master mode and add the panel device that will
register as a slave.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20200908200101.64974-6-eajames@linux.ibm.com


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