netem: fix gemodel loss generator

Patch from developers of the alternative loss models, downloaded from:
   http://netgroup.uniroma2.it/twiki/bin/view.cgi/Main/NetemCLG



 "in case 2, of the switch we change the direction of the inequality to
  net_random()>clg->a3, because clg->a3 is h in the GE model and when h
  is 0 all packets will be lost."

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>