drm/amdgpu:fix wb_clear

Properly shift the index when clearing so we clear
the right bit

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Monk Liu 2017-10-17 19:18:56 +08:00 • committed by Alex Deucher
commit 63ae07ca4f