[PKT_SCHED] sch_atm: style cleanup

ATM scheduler clean house:
  * get rid of printk and qdisc_priv() wrapper
  * split some assignment in if() statements
  * whitespace and line breaks.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>