UPSTREAM: irqchip/gic-v3: Refactor gic_of_init() for GICv3 driver

UPSTREAM: irqchip/gic-v3: Refactor gic_of_init() for GICv3 driver

Isolate hardware abstraction (FDT) code to gic_of_init().
Rest of the logic goes to gic_init_bases() and expects well
defined data to initialize GIC properly. The same solution
is used for GICv2 driver.

This is needed for ACPI initialization later.

Change-Id: I61fcbd96ecd2dc8130cdd2d6ce79841eb184e87b
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
(cherry picked from commit db57d7460ea74de2204ddc303520753f256ea67d)