[media] dib0700: do not lock interruptible on tear-down paths

When mutex_lock_interruptible is used on paths where a signal can be
pending, the device is not closed properly and cannot be reused.
This usually happens when you start tzap for example and send it a
TERM signal. The signal is pending while tear-down routines are
called. Hence streaming is not properly stopped in that case. And
the device stops working from that moment on.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>