ARM: dts: aspeed: mtmitchell: Update ADC sensors for Mt.Mitchell DVT systems

Change to use I2C ADC controller (ltc2497) for Mt.Mitchell DVT and
later hardware.

Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
Link: https://lore.kernel.org/r/20230620092537.20007-3-chanh@os.amperecomputing.com


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