[PATCH] USB Gadget: RNDIS/Ethernet Gadget Driver (2/2)

This updates the existing Ethernet gadget driver to
support an additional RNDIS configuration on all
current USB controllers that can support one.

It also includes a bit more work to address the complex
autoconfiguration of this driver.  Needs testing on PXA.

Patch (mostly) contributed by Robert Schwebel, and developed
with support from Auerswald GmbH.