drivers: i2c: add brcm iproc I2C driver support

Add I2C driver support for Broadcom iproc-based socs.

Signed-off-by: Arjun Jyothi <arjun.jyothi@broadcom.com>
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Signed-off-by: Sheetal Tigadoli <sheetal.tigadoli@broadcom.com>
Signed-off-by: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
Reviewed-by: Heiko Schocher <hs@denx.de>