This patch deprecates the legacy ARM GIC driver and related header files
(arm_gic.h, gic_v2.h, gic_v3.h). For GICv2 systems, platform ports should
use the GICv2 driver in include/drivers/arm/gicv2.h and for GICv3 systems,
platform ports should use the GICv3 driver in include/drivers/arm/gicv3.h

NOTE: The ARM Legacy GIC drivers have been deprecated with this patch.
Platform ports are encouraged to migrate to the new GIC drivers.

Change-Id: Ic0460ef0427b54a6aac476279a7f29b81943e942