gpu: host1x: Correct host1x_job_pin() error handling

In case of relocations / waitchecks patching failure the jobs pins stay
referenced till DRM file get closed, wasting memory. Add the missed
unpinning.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Erik Faye-Lund <kusmabite@gmail.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>