[media] cx23885: Avoid incorrect error handling and reporting

Previous driver over-reported errors and stopped the video fifo
(causing video to stop) if 1) A risc error occured 2) The risc processor
detected that it has missing lines in the video frame 3) The risc fifo
is about to overflow.

The previous driver reported all three of these cases as risc errors
when this is technically not correct. So, the function was cleaned up.

1. Ensure that risc opcode related errors are correctly shown as such,
   and not overly reported for non-risc-opcode cases.
2. Ensure that line sync and overflow errors are not reported as opcode errors.
3. Ensure that only the risc-op-code case can stop the fifo and dump channel
   / risc processor information.

The net result is that if video becomes unstable, cable disconnect, this will
not trigger a stop of the video firmware (due to missing lines errors).

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