ARM: mvebu: second PCIe unit of Armada XP mv78230 is only x1 capable

Various Marvell datasheets advertise second PCIe unit of mv78230
flavour of Armada XP as x4/quad x1 capable. This second unit is in
fact only x1 capable. This patch fixes current mv78230 .dtsi to
reflect that, i.e. makes 1.0 the second interface (instead of 2.0
at the moment). This was successfully tested on a mv78230-based
ReadyNAS 2120 platform with a x1 device (FL1009 XHCI controller)
connected to this second interface.

Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: <stable@vger.kernel.org> # v3.10.x
Signed-off-by: Jason Cooper <jason@lakedaemon.net>