The imx6qdl-sabreauto boards have a pcie slot so let's enable it.

Tested on imx6dl-sabreauto with an atk9k wifi card; scanning works.

There are unhandled differences for imx6qp but imx6qp-sabreauto.dts
already contains a snippet explicitly disabling the &pcie node so that
can be dealt with later.
Signed-off-by: NLeonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>