usb ethernet gadget: split CDC Subset function

This is a simple "CDC Subset" (and MCCI "SAFE") function driver, extracted
from the all-in-one Ethernet gadget driver.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/u_ether.h b/drivers/usb/gadget/u_ether.h
index ca8ce46..0ef8234 100644
--- a/drivers/usb/gadget/u_ether.h
+++ b/drivers/usb/gadget/u_ether.h
@@ -80,4 +80,7 @@
 struct net_device *gether_connect(struct gether *);
 void gether_disconnect(struct gether *);
 
+/* each configuration may bind one instance of an ethernet link */
+int geth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
+
 #endif /* __U_ETHER_H */