ARM: dts: aspeed: everest: Add RTC

Add the RTC at the appropriate I2C bus and address.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20210329150020.13632-20-eajames@linux.ibm.com


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