i2c: bcm-kona: Introduce Broadcom I2C Driver

Introduce support for Broadcom Serial Controller (BSC) I2C bus found
in the Kona family of Mobile SoCs.  FIFO hardware is utilized but only
standard mode (100kHz), fast mode (400kHz), fast mode plus (1MHz), and
I2C high-speed (3.4 MHz) bus speeds are supported.

Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
[wsa: fixed Kconfig sorting, squashed broken out patches into one]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>