[media] saa7134: move saa7134_pgtable to saa7134_dmaqueue

All dmaqueue's use saa7134_pgtable, so move it into struct saa7134_dmaqueue.
The videobuf_queue priv_data field now points to the dmaqueue struct.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>