ARM: mvebu: re-enable PCIe on Armada 370 DB

Commit 14fd8ed0 ("ARM: mvebu: Relocate Armada 370/XP PCIe
device tree nodes") relocated the PCIe controller DT nodes one level
up in the Device Tree, to reflect a more correct representation of the
hardware introduced by the mvebu-mbus Device Tree binding.

However, while most of the boards were properly adjusted accordingly,
the Armada 370 DB board was left unchanged, and therefore, PCIe is
seen as not enabled on this board. This patch fixes that by moving the
PCIe controller node one level-up in armada-370-db.dts.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: <stable@vger.kernel.org> # v3.12+
Fixes: 14fd8ed0 "ARM: mvebu: Relocate Armada 370/XP PCIe device tree nodes"
Signed-off-by: Jason Cooper <jason@lakedaemon.net>