[media] fix MSI DIGIVOX mini III remote controller power buttons

Fix power button mappings as defined in
http://www.linuxtv.org/wiki/index.php/Remote_Controllers



Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>