msm: camera: sensor: register sensor driver as i2c driver

Call i2c_add_driver to register the sensor driver as i2c driver.
This is needed to handle slaves that use QUP instead of CCI
for I2C operations

Change-Id: Id3ac0c501911dc9ccf52c12a6c1fc6ed6e669a4c
Signed-off-by: Rajesh Bondugula <rajeshb@codeaurora.org>