V4L/DVB (13646): sh_mobile_ceu_camera: do not mark host occupied, when adding a client fails

Currently, if resetting the host interface, when adding a new client, fails, a
negative error code is returned, but the host is still marked as occupied. Fix
this bug.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>