staging: vt6655: Fix Warning on boot handle_irq_event_percpu.

staging: vt6655: Fix Warning on boot handle_irq_event_percpu.

commit 6cff1f6ad4c615319c1a146b2aa0af1043c5e9f5 upstream.

WARNING: CPU: 0 PID: 929 at /home/apw/COD/linux/kernel/irq/handle.c:147 handle_irq_event_percpu+0x1d1/0x1e0()
irq 17 handler device_intr+0x0/0xa80 [vt6655_stage] enabled interrupts

Using spin_lock_irqsave appears to fix this.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>