gpu: host1x: Always return syncpoint value when waiting

The new TegraDRM UAPI uses syncpoint waiting with timeout set to
zero to indicate reading the syncpoint value. To support that we
need to return the syncpoint value always when waiting.

Fixes: 44e96138

 ("drm/tegra: Implement syncpoint wait UAPI")
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>