drm/radeon: bail early from enable ss in certain cases
drm/radeon: bail early from enable ss in certain cases

If the ss percentage is 0 or we are using external ss,
just bail when enabling ss.  We disable it explicitly
earlier in the modeset already.

Signed-off-by: Alex Deucher <08dc22c6156113f2deff178e35e3ed9b24d6af9e@amd.com>

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