[PATCH] Char: stallion, brd struct locking

Since assigning of stl_brds[brdnr] is racy, add locking to this critical
section.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>