net: mvneta: introduce compatible string "marvell, armada-xp-neta"

The mvneta driver supports the Ethernet IP found in the Armada 370, XP,
380 and 385 SoCs. Since at least one more hardware feature is available
for the Armada XP SoCs then a way to identify them is needed.

This patch introduces a new compatible string "marvell,armada-xp-neta".

Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Fixes: c5aff182 ("net: mvneta: driver for Marvell Armada 370/XP network unit")
Cc: <stable@vger.kernel.org> # v3.8+
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>