Fix typo/etc in module/zfs/zfs_ctldir.c

Drop duplicated phrases in comments.

Also drop an obsolete comment "Perform a mount of the associated...",
as all it does now is get objid from DMU and lookup incore inode.

Reviewed-by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Closes openzfs#8707

module/zfs/zfs_ctldir.c

@@ -56,12 +56,12 @@
  * corresponding inode.
  *
  * All mounts are handled automatically by an user mode helper which invokes
- * the mount mount procedure.  Unmounts are handled by allowing the mount
+ * the mount procedure.  Unmounts are handled by allowing the mount
  * point to expire so the kernel may automatically unmount it.
  *
  * The '.zfs', '.zfs/snapshot', and all directories created under
  * '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') all share the same
- * share the same zfsvfs_t as the head filesystem (what '.zfs' lives under).
+ * zfsvfs_t as the head filesystem (what '.zfs' lives under).
  *
  * File systems mounted on top of the '.zfs/snapshot/<snapname>' paths
  * (ie: snapshots) are complete ZFS filesystems and have their own unique
@@ -148,7 +148,7 @@ zfsctl_snapshot_alloc(char *full_name, char *full_path, spa_t *spa,
 }
 
 /*
- * Free a zfs_snapentry_t the called must ensure there are no active
+ * Free a zfs_snapentry_t the caller must ensure there are no active
  * references.
  */
 static void
@@ -810,7 +810,6 @@ zfsctl_root_lookup(struct inode *dip, char *name, struct inode **ipp,
 /*
  * Lookup entry point for the 'snapshot' directory.  Try to open the
  * snapshot if it exist, creating the pseudo filesystem inode as necessary.
- * Perform a mount of the associated dataset on top of the inode.
  */
 int
 zfsctl_snapdir_lookup(struct inode *dip, char *name, struct inode **ipp,