i2c: brcmstb: Add Broadcom settop SoC i2c controller driver

Adding support for i2c controller driver for Broadcom settop
SoCs.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
[wsa: removed superfluous owner in platform_driver]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>