Illumos #2618 arc.c mistypes in the comments

2618 arc.c mistypes in the comments

Reviewed by: Jason King <jason.brian.king@gmail.com>
Reviewed by: Josef Sipek <jeffpc@josefsipek.net>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  illumos/illumos-gate@fc98fea
  illumos changeset: 13721:5b51a16a186f
  https://www.illumos.org/issues/2618

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>

Author: bcoddens

module/zfs/arc.c

@@ -80,9 +80,9 @@
  * types of locks: 1) the hash table lock array, and 2) the
  * arc list locks.
  *
- * Buffers do not have their own mutexs, rather they rely on the
- * hash table mutexs for the bulk of their protection (i.e. most
- * fields in the arc_buf_hdr_t are protected by these mutexs).
+ * Buffers do not have their own mutexes, rather they rely on the
+ * hash table mutexes for the bulk of their protection (i.e. most
+ * fields in the arc_buf_hdr_t are protected by these mutexes).
  *
  * buf_hash_find() returns the appropriate mutex (held) when it
  * locates the requested buffer in the hash table.  It returns
@@ -2890,7 +2890,7 @@ arc_read_done(zio_t *zio)
 }
 
 /*
- * "Read" the block block at the specified DVA (in bp) via the
+ * "Read" the block at the specified DVA (in bp) via the
  * cache.  If the block is found in the cache, invoke the provided
  * callback immediately and return.  Note that the `zio' parameter
  * in the callback will be NULL in this case, since no IO was