staging: octeon: Remove USB code

Remove functions and definitions that refer to USB since the driver
doesn't support USB and it's not planned to add USB support to that
driver. So the code is just dead code which can be removed.

Cc: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Bernhard Walle <walle@corscience.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>