sched/fair: Fix nuisance kernel-doc warning

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>