cpuidle: coupled: Drop duplicate word from a comment

The double `are' is duplicated in the comment, remove one.
Signed-off-by: NJason Wang <wangborong@cdjrlc.com>
[ rjw: New subject ]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/coupled.c

@@ -54,7 +54,7 @@
  * variable is not locked.  It is only written from the cpu that
  * it stores (or by the on/offlining cpu if that cpu is offline),
  * and only read after all the cpus are ready for the coupled idle
- * state are are no longer updating it.
+ * state are no longer updating it.
  *
  * Three atomic counters are used.  alive_count tracks the number
  * of cpus in the coupled set that are currently or soon will be