V4L/DVB (3271): Update tuner comments

Right now, all tuners are using the first tuner_params[]
array element for analog mode. We are now ready to begin merging
similar tuner definitions together, such that each tuner definition
will have a tuner_params struct for each available video standard.
The tuner_params[] array element will be chosen based on the video
standard in use.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>