Additional cleanups to tuner-core

Hans Verkuils gave me some feedback about the last series at the ML, and, due to that, I've added a few more cleanup patches at the series.

Basically, he poined me two issues:

- DIGITAL_TV is not used at tuner core;
- tuner_lookup shouldn't touch at t->standby.

This series cleans the code to address the above issues, and also do a few other cleanups to better document the code, without changing any functionality.

I also extended my tests with some other devices. The tuner-core was tested with:
- cx88: Pixelview Ultra Pro: A TNF analog tuner + tea5767;
- em28xx: WinTV USB2: an analog tuner with tda9887;
- em28xx: HVR950: xc2028 based tuner;
- cx231xx: Pixelview SBTVD Hybrid: tda18271 tuner.

On all the tests, tuner-core behave well. So, I'm committing the entire tuner-core series of patches, for people to test them with other devices, but, based on my tests, I don't think that the changes would cause any regressions.

Mauro Carvalho Chehab (4):
[media] tuner-core: remove usage of DIGITAL_TV [media] tuner-core: Improve function documentation [media] tuner-core: Rearrange some functions to better document [media] tuner-core: Don't touch at standby during tuner_lookup

 drivers/media/video/au0828/au0828-cards.c   |    3 +-
 drivers/media/video/bt8xx/bttv-cards.c      |    2 +-
 drivers/media/video/cx88/cx88-cards.c       |    4 +-
 drivers/media/video/saa7134/saa7134-cards.c |    4 +-
 drivers/media/video/tuner-core.c            |  310 ++++++++++++++++++---------
 5 files changed, 209 insertions(+), 114 deletions(-)