drm/nouveau/pmu: do not assume a PMU is present
drm/nouveau/pmu: do not assume a PMU is present

Some devices may not have a PMU. Avoid a NULL pointer dereference in
such cases by checking whether the pointer given to nvkm_pmu_pgob() is
valid.

Signed-off-by: Alexandre Courbot <301cd6a3ea50a894b4b51e385c5eb12b9a4ffc0c@nvidia.com>
Signed-off-by: Ben Skeggs <d9f27fb07c1e9f131223ad827fa5179f3846c30b@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs