v2: fix bug in register mask setting.
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Acked-by: NJammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: NEric Huang <JinHuiEric.Huang@amd.com>