V4L/DVB (12582): The current AVC debugging can clog the log down a lot since many

applications tend to check the signal strength very often.  This patch
enables users to select which AVC messages to log using a bitmask.  In
addition, it also enables the possibility to debug application PMTs sent
to the driver.  This will be usable since the CA support is still poorly
tested for lots of CAMs and CA systems.

Signed-off-by: Henrik Kurelid <henrik@kurelid.se>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>