sched: Fix various typos in comments

Go over the scheduler source code and fix common typos
in comments - and a typo in an actual variable name.

No change in functionality intended.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/sched/stat.h b/include/linux/sched/stat.h
index f30954c..5682864 100644
--- a/include/linux/sched/stat.h
+++ b/include/linux/sched/stat.h
@@ -8,7 +8,7 @@
  * Various counters maintained by the scheduler and fork(),
  * exposed via /proc, sys.c or used by drivers via these APIs.
  *
- * ( Note that all these values are aquired without locking,
+ * ( Note that all these values are acquired without locking,
  *   so they can only be relied on in narrow circumstances. )
  */