Use PCIe support for MT7628AN also on MT7688.

Tested on WRTNODE2R.
Signed-off-by: NDaniel Golle <daniel@makrotopia.org>
Cc: John Crispin <john@phrozen.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: linux-mediatek@lists.infradead.org
Patchwork: https://patchwork.linux-mips.org/patch/16223/Signed-off-by: NJames Hogan <jhogan@kernel.org>