media: dvbdev: Fix memleak in dvb_register_device

When device_create() fails, dvbdev and dvbdevfops should
be freed just like when dvb_register_media_device() fails.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>