V4L/DVB (10947): Auto-load videodev module when device opened.

The videodev module is missing the char-major-81-* alias that would
cause it to be auto-loaded when a device of that type is opened.  This
patch adds the alias.

Signed-off-by: Scott James Remnant <scott@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>