V4L/DVB: cx88: increase BUFFER_TIMEOUT to 2 seconds

When temporarily there is no video signal, sometimes it takes more than 0.5
secs for the cx88 chip to generate a single frame. If a dma timeout occurs
during recording, it confuses the recording application (at least mencoder)
and the recording stops.

Since there is already an #if 0 for 2 seconds buffer timeout in the code
at the -hg development tree, re-enabling that seemed the most simple
solution.

Signed-off-by: Marton Balint <cus@fazekas.hu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>