orinoco: add orinoco_usb driver

This driver uses the core orinoco modules for the bulk of
the functionality. The low level hermes routines (for local bus
cards) are replaced, the driver supplies its own ndo_xmit_start
function, and locking is done with the _bh variant.

Some recent functionality is not available to the USB cards yet
(firmware loading and WPA).

Out-of-tree driver originally written by Manuel Estrada Sainz.

Thanks to Mark Davis for supplying hardware to test the updates.

Signed-off-by: David Kilroy <kilroyd@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>