drm/vc4: Fix YUV plane handling when planes are in different buffers

drm/vc4: Fix YUV plane handling when planes are in different buffers

commit 6b77b16de75a6efc0870b1fa467209387cbee8f3 upstream.

YUV images can either be presented as one allocation with offsets
for the different planes, or multiple allocations with 0 offsets.

The driver only ever calls drm_fb_[dma|cma]_get_gem_obj with plane
index 0, therefore any application using the second approach was
incorrectly rendered.

Correctly determine the address for each plane, removing the
assumption that the base address is the same for each.

Fixes: fc04023fafec ("drm/vc4: Add support for YUV planes.")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20230127155708.454704-1-maxime@cerno.tech
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>