jffs2: Drop bogus if in comment

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Brian Norris <computersforpeace@gmail.com>