[PATCH] dvb: determine tuner write method based on nxt chip

- Add support for AVerTVHD MCE a180.
- Instead of determining how to write to the tuner based on which NIM
  is being used, make this determination based on whether the chip is a
  NXT2002 or NXT2004.
- If NXT2004, write directly to tuner. If NXT2002, write through NXT chip.

Signed-off-by: Michael Krufky <mkrufky@m1k.net>
Cc: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>