sched/fair: Fix nuisance kernel-doc warning

Work around kernel-doc warning ('*' in Sphinx doc means "emphasis"):

  ../kernel/sched/fair.c:7584: WARNING: Inline emphasis start-string without end-string.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f18b30f9-6251-6d86-9d44-16501e386891@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -7719,7 +7719,7 @@ next_group:
  * number.
  *
  * Return: 1 when packing is required and a task should be moved to
- * this CPU.  The amount of the imbalance is returned in *imbalance.
+ * this CPU.  The amount of the imbalance is returned in env->imbalance.
  *
  * @env: The load balancing environment.
  * @sds: Statistics of the sched_domain which is to be packed