This patch moves all firmware load responsibility into the interface-specific
code and gets rid of the firmware pointer in the generic card structure.  It
also removes 3 fairly unecessary callbacks: hw_register_dev, hw_unregister_dev,
and hw_prog_firmware.  It also makes the init sequence from interface
probe functions more logical, as there are paired add/remove and start/stop
calls into generic libertas code.

Because the USB driver code uses the same TX URB callback for both firmware
upload (where the generic libertas structure isn't initialized yet) and for
normal operation (where it is), some bits of USB code have to deal with
'priv' being NULL.  All USB firmware upload bits have been changed to not
require 'priv' at all, but simply the USB card structure.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>