[media] saa7164: add firmware debug message collection and procfs changes

Check for PROCFS and dynamically adjust code.
Cache some PCIe values in the device context.
Provide a mechanism to collect the debug messages
coming from the firmware.

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>