V4L/DVB (8123): Add support for em2860 based PointNix Intra-Oral Camera

em28xx-cards.c
em28xx-input.c
em28xx-video.c
em28xx.h
 - Add support for the PointNix Intra-Oral Camera, which required addition of
   a construct for reading the "snapshot" button (provided on the em2860 and
   em2880 chips, but this is the first case where I have seen it actually used
   in a product). The button is wired to pin 56 on the em2880.

   http://www.pointnix.com/ENG/dental/product_02.asp

   Thanks to Roberto Mantovani <rmantovani@libero.it> for testing the changes

Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/Documentation/video4linux/CARDLIST.em28xx b/Documentation/video4linux/CARDLIST.em28xx
index c7e2394..1059146 100644
--- a/Documentation/video4linux/CARDLIST.em28xx
+++ b/Documentation/video4linux/CARDLIST.em28xx
@@ -17,3 +17,4 @@
  16 -> Hauppauge WinTV HVR 950                  (em2880)        [2040:6513,2040:6517,2040:651b,2040:651f]
  17 -> Pinnacle PCTV HD Pro Stick               (em2880)        [2304:0227]
  18 -> Hauppauge WinTV HVR 900 (R2)             (em2880)        [2040:6502]
+ 19 -> PointNix Intra-Oral Camera               (em2860)