Fix spelling

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Haakan T Johansson <f96hajo@chalmers.se>
Closes #5547 
Closes #5543

module/zfs/rrwlock.c

@@ -313,8 +313,8 @@ rrw_tsd_destroy(void *arg)
  * The idea is to split single busy lock into array of locks, so that
  * each reader can lock only one of them for read, depending on result
  * of simple hash function.  That proportionally reduces lock congestion.
- * Writer same time has to sequentially aquire write on all the locks.
- * That makes write aquisition proportionally slower, but in places where
+ * Writer at the same time has to sequentially acquire write on all the locks.
+ * That makes write acquisition proportionally slower, but in places where
  * it is used (filesystem unmount) performance is not critical.
  *
  * All the functions below are direct wrappers around functions above.