[PATCH] ipw2200 locking fix

Well, this is not 100% if when the card fires two consecutive
interrupts. Though unlikely, it's better to protect early than seeing
some "weird" bugs one day. I proposed attached patch. If you can help to
test, that will be appreciated (I cannot see the lockdep warning on my
box somehow).

Cc: Frederik Deweerdt <deweerdt@free.fr>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>