irqchip/aspeed-vic: Add irq controller for Aspeed

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lkml.kernel.org/r/1463064193-2178-3-git-send-email-joel@jms.id.au


Signed-off-by: Jason Cooper <jason@lakedaemon.net>