media: media/v4l2-core: Add enum V4L2_FWNODE_BUS_TYPE_DPI

As V4L2_FWNODE_BUS_TYPE_PARALLEL is not used for DPI interface, this
patch add V4L2_FWNODE_BUS_TYPE_DPI for video DPI interface.

Signed-off-by: Xin Ji <xji@analogixsemi.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>