drm/amdgpu: fix NULL in vm_grab_id while S3 back

BugLink: http://bugs.launchpad.net/bugs/1546572

vm_manager_fini shouldn't be in suspend phase.
Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Ken Wang  <Qingqing.Wang@amd.com>
(cherry picked from commit e1de7415)
Signed-off-by: Alberto Milone <alberto.milone@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c

@@ -1005,7 +1005,6 @@ static int gmc_v7_0_sw_fini(void *handle)
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
 	if (adev->vm_manager.enabled) {
-		amdgpu_vm_manager_fini(adev);
 		gmc_v7_0_vm_fini(adev);
 		adev->vm_manager.enabled = false;
 	}

drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c

@@ -1009,7 +1009,6 @@ static int gmc_v8_0_suspend(void *handle)
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
 	if (adev->vm_manager.enabled) {
-		amdgpu_vm_manager_fini(adev);
 		gmc_v8_0_vm_fini(adev);
 		adev->vm_manager.enabled = false;
 	}