V4L/DVB (6988): tda18271: give calibration debug a separate debug mask

We don't usually want to see the calibration debug messages, but sometimes
it is useful.  Assign it to a separate debug mask.

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