[media] exynos4-is: Add FIMC-IS ISP I2C bus driver

This patch adds the ISP I2C bus controller driver files.
Creating a standard I2C bus adapter, even if the driver doesn't
actually communicate with the hardware and it is instead
controlled by the ISP firmware running on the Cortex-A5, allows
to use standard hardware description in the device tree. As the
sensor would have actually had a standard V4L2 sub-device driver
run on the host CPU.
This approach allows to adapt the driver with a relatively small
effort should the Imaging Subsystem architecture change so that
the I2C bus is handled by the host's CPU OS, rather than the
internal FIMC-IS ARM CPU firmware. The image sensor driver could
be a standard I2C client driver, as in case of most existing
image sensors.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>