drm/amdgpu: just suspend the hw on pci shutdown

We can't just reuse pci_remove as there may be userspace still
doing things.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98638
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97980
Reviewed-by: Christian König <christian.koenig@amd.com>
Reported-and-tested-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 496f72b..05c2850 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -2472,6 +2472,7 @@ void amdgpu_driver_postclose_kms(struct drm_device *dev,
 				 struct drm_file *file_priv);
 void amdgpu_driver_preclose_kms(struct drm_device *dev,
 				struct drm_file *file_priv);
+int amdgpu_suspend(struct amdgpu_device *adev);
 int amdgpu_device_suspend(struct drm_device *dev, bool suspend, bool fbcon);
 int amdgpu_device_resume(struct drm_device *dev, bool resume, bool fbcon);
 u32 amdgpu_get_vblank_counter_kms(struct drm_device *dev, unsigned int pipe);