msm_fb: display: Add I2C interface to Toshiba DSI-to-LVDS driver.

The Toshiba bridge has both DSI and I2C interfaces.
The DSI interface is used for configuring the bridge registers
during setup.
However, when video is running via the DSI interface
then the I2C interface is used for read/write
the Toshiba bridge registers.

Change-Id: I6e90244948e09710fb9f55f1d828e73e1218e266
Signed-off-by: Amir Samuelov <amirs@codeaurora.org>