drm/amd/display: Do not put drm_atomic_state on resume

drm_atomic_helper_resume now puts it for us. See relevant patch here:
https://lists.freedesktop.org/archives/dri-devel/2017-October/154268.html

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -716,7 +716,6 @@ int amdgpu_dm_display_resume(struct amdgpu_device *adev)
 
 	ret = drm_atomic_helper_resume(ddev, adev->dm.cached_state);
 
-	drm_atomic_state_put(adev->dm.cached_state);
 	adev->dm.cached_state = NULL;
 
 	amdgpu_dm_irq_resume_late(adev);