MAINTAINERS: xgene: Add driver and documentation path

BugLink: https://launchpad.net/bugs/1632739

Added path to the MDIO driver and Documentation file.
Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 2efccc60 yakkety)
Signed-off-by: Craig Magina <craig.magina@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

MAINTAINERS

@@ -808,7 +808,9 @@ M:	Iyappan Subramanian <isubramanian@apm.com>
 M:	Keyur Chudgar <kchudgar@apm.com>
 S:	Supported
 F:	drivers/net/ethernet/apm/xgene/
+F:	drivers/net/phy/mdio-xgene.c
 F:	Documentation/devicetree/bindings/net/apm-xgene-enet.txt
+F:	Documentation/devicetree/bindings/net/apm-xgene-mdio.txt
 
 APTINA CAMERA SENSOR PLL
 M:	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>