[PKT_SCHED]: Distribution table fixes for netem.

[PKT_SCHED]: Distribution table fixes for netem.

Fix some issues with netem.
 * fix memory link in q_destroy where distribution table not freed
 * fix math error in tabledist that made it work for only small values
 * change API for distribution table so scaling factor is constant and
   table size is determined by looking at the rtnetlink payload size.
   this is faster and simpler. Since haven't actually released the tools to load
   the table yet, this is the chance to get it right ;-)

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