i2400m/USB: header for the USB bus driver

This contains the common function declaration and constants for the
USB driver for the 2400m Wireless WiMAX Connection, as well as it's
debug level settings.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>