V4L/DVB (6578): dvb-usb: make some debug vars static

This patch makes some needlessly global debug variables static.

opera1.h became so small that I removed it.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Reviewed-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>