Add I2C support for Engicam Is.IoT MX6UL module.

isiotmx6ul> i2c bus
Bus 0:  i2c@021a0000
Bus 1:  i2c@021a4000
isiotmx6ul> i2c dev 0
Setting bus to 0
isiotmx6ul> i2c dev
Current bus is 0
isiotmx6ul> i2c speed 100000
Setting bus speed to 100000 Hz
isiotmx6ul> i2c probe
Valid chip addresses: 00 2C 44 78
isiotmx6ul> i2c md 2C 0xff
00ff: 00 00 00 00 0f f0 01 64 ff ff 00 00 00 00 00 00    .......d........

Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed-by: NStefano Babic <sbabic@denx.de>
Signed-off-by: NJagan Teki <jagan@amarulasolutions.com>