media: sun6i: Add H3 compatible

The CSI controller found on the H3 (and H5) is a reduced version of the
one found on the A31. It only has 1 channel, instead of 4 channels for
time-multiplexed BT.656. Since the H3 is a reduced version, it cannot
"fallback" to a compatible that implements more features than it
supports.

Add a compatible string entry for the H3.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>