staging: emxx_udc: Add Emma Mobile USB Gadget driver

Add the emxx_udc driver to staging based on an old linux-2.6.35.7
android tree. The driver has been brushed up slightly to complile
but it is still in great need of cleanup.

At this point DT bindings are clearly lacking and I doubt that the
driver even can run with multiple instances (global variables, hurray!).

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>