page fault in ugenpoll()

[Dirk GOUDERS]

 > The control endpoint /dev/ugen0 does not support polling. But 
 > polling /dev/ugen0.X should work, where "X" is a number.
 > 
 > "ugenpoll()" in "/sys/dev/usb/ugen.c" should have something like this added:
 > 
 > if(control endpoint) return POLLNVAL; /* and not "return EIO;" */
 > 
 > Please file a PR on this issue using:
 > 
 > >Category:      usb

Thank you.
I modified ugen.c in the way you suggested and filed a PR.

Dirk