[media] stk1160: Remove redundant vb2_buf payload set

Calling vb2_set_plane_payload is enough, there's no need to
set the planes[] bytesused field. Remove it.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>