media: vivid: dev->bitmap_cap wasn't freed in all cases

Whenever the compose width/height values change, the dev->bitmap_cap
vmalloc'ed array must be freed and dev->bitmap_cap set to NULL.

This was done in some places, but not all. This is only an issue if
overlay support is enabled and the bitmap clipping is used.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: ef834f7836ec ([media] vivid: add the video capture and output parts)
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
