This patch fixes bug in PPC4xx disable_irq implementation.  We need to ACK
parent UIC to prevent false triggering in case IRQ we just disabled was
already pending.
Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>