cx18: Have CX23418 release buffers at end of capture.  The CX23418 reuses task
handles so we need to have it release the buffers associated with a task handle
at the end of a capture.  If we don't, buffer ids used for one type of stream
in the driver (MPEG, TS, PCM), could be used for another type of stream by the
CX23418, if a previously used handle is assigned to a different type of stream.
The driver would drop valid buffers when this happened.
Signed-off-by: NAndy Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Many thanks to Steve Toth from Hauppauge and Nattu Dakshinamurthy from
Conexant for their support. I am in particular thankful to Hauppauge
since without their help this driver would not exist. It should also
be noted that Steve did the work to get the DVB part up and running.
Thank you!
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NSteven Toth <stoth@hauppauge.com>
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NG. Andrew Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>