libertas: clean up lbs_interrupt()

Make it take struct lbs_private as argument; that's all it wants anyway,
and all callers were starting off from that. Don't wake the netif
queues, because those should be handled elsewhere. And sort out the
locking, with a big nasty warning for those who don't have the
driver_lock locked when they call it.

Oh, and fix if_cs.c to lock the driver_lock before calling it.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>