V4L/DVB (10059): dsbr100: dev_err instead of dev_warn

We should use dev_err (not dev_warn) if video_register_device fails.

Signed-off-by: Alexey Klimov <klimov.linux@gmail.com>
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>