which avoids job->vm_pd_addr be changed.

V2: pass job structure to amdgpu_vm_grab_id and amdgpu_vm_flush directly.
Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>