V4L/DVB (12567): ir-keymaps: use KEY_CAMERA for snapshots

V4L/DVB (12567): ir-keymaps: use KEY_CAMERA for snapshots

KEY_CAMERA is already used for a long time with webcam drivers to take a picture.
On other media drivers, due to the lack of a snapshot button, random KEY codes
were sent, being KEY_SHUFFLE the most used one, probably due to cut-and-paste
from other remotes, since one of them uses the same key for snapshot and shuffle.

The better is to use KEY_CAMERA on all drivers solving this issue. This
follows the IR standard map as defined at:
	http://linuxtv.org/wiki/index.php/Remote_Controllers

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>