usb: xhci-mvebu: Add Armada 8K to compatiblity list

usb: xhci-mvebu: Add Armada 8K to compatiblity list

To enable this driver on Armada 7K/8K this patch adds the compatibility
property to the list.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Omri Itach <omrii@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>