nfs: fix spellint typo in pnfs.c

Change the comment typo: "manger" -> "manager".

Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/pnfs.c

@@ -902,7 +902,7 @@ restart:
 }
 
 /*
- * Called by the state manger to remove all layouts established under an
+ * Called by the state manager to remove all layouts established under an
  * expired lease.
  */
 void