hw/intc: Add (new) ASPEED VIC device model

Implement a basic ASPEED VIC device model for the AST2400 SoC[1], with
enough functionality to boot an aspeed_defconfig Linux kernel. The model
implements the 'new' (revised) register set: While the hardware exposes
both the new and legacy register sets, accesses to the model's legacy
register set will not be serviced (however the access will be logged).

[1] http://www.aspeedtech.com/products.php?fPath=20&rId=376

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Message-id: 1458096317-25223-3-git-send-email-andrew@aj.id.au
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
