drm/radeon: fix S/R on VM systems (cayman/TN/SI)

We weren't properly tearing down the VM sub-alloctor
on suspend leading to bogus VM PTs on resume.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=60439Reviewed-by: Christian König <christian.koenig@amd.com>
Tested-by: Dmitry Cherkasov <Dmitrii.Cherkasov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/ni.c

@@ -1771,6 +1771,7 @@ int cayman_resume(struct radeon_device *rdev)
 int cayman_suspend(struct radeon_device *rdev)
 {
 	r600_audio_fini(rdev);
+	radeon_vm_manager_fini(rdev);
 	cayman_cp_enable(rdev, false);
 	cayman_dma_stop(rdev);
 	evergreen_irq_suspend(rdev);

drivers/gpu/drm/radeon/si.c

@@ -4469,6 +4469,7 @@ int si_resume(struct radeon_device *rdev)
 
 int si_suspend(struct radeon_device *rdev)
 {
+	radeon_vm_manager_fini(rdev);
 	si_cp_enable(rdev, false);
 	cayman_dma_stop(rdev);
 	si_irq_suspend(rdev);