commit 1bced75f upstream.

it is required if a platform supports PCIe root complex
core voltage reduction. After receiving this notification,
SBIOS can apply default PCIe root complex power policy.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>