The legacy image for the UniElec U7623-02 until now included
kmod-ata-ahci-mtk. The MT7623 chip doesn't have that IP and that
board uses a PCIe-connected AHCI controller for the SATA port and
mSATA-pins of the mPCIe socket. Hence include kmod-ata-ahci instead.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>