staging: fix more ET131X build errors

ET131X is a network device, so it should depend on
NETDEVICES. (This part won't be needed when the driver
moves to drivers/net/.) It also uses PHYLIB interfaces,
so it should select PHYLIB. Fixes these build errors:

ERROR: "phy_connect" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_find_first" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "mdiobus_register" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "mdiobus_alloc" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_stop" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_start" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "mdiobus_free" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "mdiobus_unregister" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_print_status" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_ethtool_gset" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_ethtool_sset" [drivers/staging/et131x/et131x.ko] undefined!
ERROR: "phy_mii_ioctl" [drivers/staging/et131x/et131x.ko] undefined!

Signed-off-by: Randy Dunlap <[e-mail]>
Acked-by: : Mark Einon <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/et131x/Kconfig

···
 config ET131X
 	tristate "Agere ET-1310 Gigabit Ethernet support"
-	depends on PCI && NET
+	depends on PCI && NET && NETDEVICES
+	select PHYLIB
 	default n
 	---help---
 	  This driver supports Agere ET-1310 ethernet adapters.