drm/amdgpu/powerplay: FEATURE_MASK is 64 bit so use ULL

ULL is needed for 32 bit arches.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>