sched: add credits for RT balancing improvements

add credits for RT balancing improvements.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -22,6 +22,8 @@
  *              by Peter Williams
  *  2007-05-06  Interactivity improvements to CFS by Mike Galbraith
  *  2007-07-01  Group scheduling enhancements by Srivatsa Vaddagiri
+ *  2007-11-29  RT balancing improvements by Steven Rostedt, Gregory Haskins,
+ *              Thomas Gleixner, Mike Kravetz
  */
 
 #include <linux/mm.h>