imx6: icorem6: Add I2C support

Add I2C support for Engicam i.CoreM6 qdl board.

icorem6qdl> i2c bus
Bus 0:  i2c@021a0000
Bus 1:  i2c@021a4000
Bus 2:  i2c@021a8000
icorem6qdl> i2c dev 2
Setting bus to 2
icorem6qdl> i2c speed 100000
Setting bus speed to 100000 Hz
icorem6qdl> i2c probe
Valid chip addresses: 2C
icorem6qdl> i2c md 2C 0xff
00ff: 00 00 00 00 0f f0 01 64 ff ff 00 00 00 00 00 00    .......d........

Cc: Stefano Babic <sbabic@denx.de>
Cc: Heiko Schocher <hs@denx.de>
Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Heiko Schocher <hs@denx.de>