sh: off by one BUG_ON() in setup_bootmem_node()

This off by one bug is harmless but it upsets the static checkers and the
code is obvious so it doesn't hurt to fix it.  The Smatch warning is:

    arch/sh/mm/numa.c:47 setup_bootmem_node()
    error: buffer overflow 'node_data' 1024 <= 1024

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>