drm/sun4i: frontend: Pass DRM format info to input format helpers

The helper returning the input mode needs to know the number of planes
for the provided format. Passing the fourcc requires iterating through
the format info list in order to return the number of planes.

Pass the DRM format info structure directly instead to all helpers
related to configuring the input format, since it's available to the
caller. Also rename the input format in the caller function to keep
things consistent.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190118145133.21281-5-paul.kocialkowski@bootlin.com