ARM: dts: aspeed: everest: Add I2C bus 15 muxes

Add the muxes that are attached on I2C bus 15.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20210903214836.48286-3-eajames@linux.ibm.com


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