ARM: dts: sunxi: h3/h5: Drop A31 fallback compatible for CSI controller

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.

Drop the A31 fallback compatible.

Fixes: f89120b6 ("ARM: dts: sun8i: Add the H3/H5 CSI controller")
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>