OMAPDSS: panel-dvi: Add Kconfig dependency on I2C

panel-dvi uses i2c, but the Kconfig didn't have dependency on I2C. Add
it.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>