We use the term "TAB" before defining it later in the document.  Fix
that up by defining it at the first location.
Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Chris Mason <clm@fb.com>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>