autofs: fix wrong ioctl documentation regarding devid

This is the same as d8732841 except that it's a different file.  A
caller has no devid input, and devid is obtained via superblock.

Link: http://lkml.kernel.org/r/148577165119.9801.16967562019122274820.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/filesystems/autofs4.txt

@@ -457,9 +457,8 @@ Commands are:
     daemon.
 - **AUTOFS_DEV_IOCTL_REQUESTER_CMD**: `path` should be a
     name within the filesystem that has been auto-mounted on.
-    arg1 is the dev number of the underlying autofs.  On successful
-    return, `arg1` and `arg2` will be the UID and GID of the process
-    which triggered that mount.
+    On successful return, `arg1` and `arg2` will be the UID and GID
+    of the process which triggered that mount.
 
 - **AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD**: Check if path is a
     mountpoint of a particular type - see separate documentation for