o propagate more errors back to caller or log them, mainly in
  av7110.c and av7110_av.c
o fix error message in StartHWFilter
o do not StopHWFilter for handle 0xffff
Signed-off-by: NWolfgang Rohdewald <wolfgang@rohdewald.de>
Signed-off-by: NJohannes Stezenbach <js@linuxtv.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>