video/matrox/matroxfb_maven: Use module_i2c_driver to register driver

Removing some boilerplate by using module_i2c_driver instead of calling
register and unregister in the otherwise empty init/exit functions.
Also removed a useless comment as suggested by Jean Delvare.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>