Add spec for the usb_gadget
Add spec for the usb_gadget

* Original author is Sebastian Andrzej Siewior <bigeasy@linutronix.de>, just
  made a version without lenghtly copyright header in the specfile to match the
  other ones.

roidayan/rtslib,Datera/rtslib,Datera/rtslib,roidayan/rtslib