ARM: mvebu: armada-xp: Move GE0/1 pinctrl settings for RGMII

Pinctrl settings for GE0 and GE1 are not only usable on RD-AXPWiFiAP.
Moreover, naming the RGMII settings pmx-ge{0,1} is not precise enough
as there is also a GMII setting for GE0.

Move the pinctrl sub-nodes to the common pinctrl node and rename them
to pmx-ge{0,1}-rgmii.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-By: Benoit Masson <yahoo@perenite.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>