usb: xhci-mtk: resume USB3 roothub first

Give USB3 devices a better chance to enumerate at USB3 speeds if
they are connected to a suspended host.
Porting from "671ffdff xhci: resume USB 3 roothub first"

Cc: <stable@vger.kernel.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>