V4L/DVB (4480): Remove null chars from dvb names

DVB null terminates its device names, which seems odd, and should be
unnecessary.
Acked-by: Alan Cox <alan@redhat.com>

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>