target-arm: Extend the gic node properties

In preparation for adding the GICv2m which requires address specifiers
and is a subnode of the gic, we extend the gic DT definition to specify
the #address-cells and #size-cells properties and add an empty ranges
property properties of the DT node, since this is required to add the
v2m node as a child of the gic node.

Note that we must also expand the irq-map to reference the gic with the
right address-cells as a consequence of this change.

Reviewed-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Message-id: 1432897270-7780-4-git-send-email-christoffer.dall@linaro.org
Suggested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>