media: dvb-core: Release semaphore on error path dvb_register_device()

commit 82163edcdfa4eb3d74516cc8e9f38dd3d039b67d upstream.

There is a missing "up_write()" here. Semaphore should be released
before returning error value.

Signed-off-by: Santosh Nayak <santoshprasadnayak@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>