V4L/DVB (12373): hdpvr: fix lock imbalances

There are many lock imbalances in this driver. Fix all found.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>