V4L/DVB (8018): Add em2860 chip ID

em28xx-cards.c
em28xx-reg.h
 - Add em2860 chip ID (seen on Pointnix Intra-Oral Camera)
   http://www.pointnix.com/ENG/dental/product_02.asp



Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>