usb: gadget: f_ncm.c added

Initial submittion of NCM link function driver.

The driver's logic is based on f_ecm driver and does not
use most of the NCM advantages like frame grouping and alignment.

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>