V4L/DVB (6725): tda18271: improve debug flexibility

converted debug module option to an or-able setting.

1 = info
2 = table map values
4 = register dumps

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