[media] videobuf2-core: fix plane_sizes handling in VIDIOC_CREATE_BUFS

The handling of q->plane_sizes was wrong in vb2_core_create_bufs().
The q->plane_sizes array was global and it was overwritten by create_bufs.
So if reqbufs was called with e.g. size 100000 then q->plane_sizes[0] would
be set to 100000. If create_bufs was called afterwards with size 200000,
then q->plane_sizes[0] would be overwritten with the new value. Calling
create_bufs again for size 100000 would cause an error since 100000 is now
less than q->plane_sizes[0].

This patch fixes this problem by 1) removing q->plane_sizes and using the
vb->planes[].length field instead, and 2) by introducing a min_length field
in struct vb2_plane. This field is set to the plane size as returned by
the queue_setup op and is the minimum required plane size. So user pointers
or dmabufs should all be at least this size.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>