drm/amdgpu: add new polaris pci id

commit 30f3984ede683b98a4e8096e200df78bf0609b4f upstream.

Add new pci id.

Reviewed-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>