[media] media: vb2: change plane sizes array to unsigned int[]

Plane sizes array was declared as unsigned long[], while unsigned int is
more than enough for storing size of the video buffer. This patch reduces
the size of the array by definiting it as unsigned int[].

Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>