cpumask: fix code comment

Fix code comment for cpumask_parse().

Link: http://lkml.kernel.org/r/71aae2c60ae5dae0cf554199ce6aea8f88c69347.1465380581.git.geliangtang@gmail.com
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/cpumask.h

@@ -579,7 +579,7 @@ static inline int cpumask_parselist_user(const char __user *buf, int len,
 }
 
 /**
- * cpumask_parse - extract a cpumask from from a string
+ * cpumask_parse - extract a cpumask from a string
  * @buf: the buffer to extract from
  * @dstp: the cpumask to set.
  *