of/platform: Drop static setup of IRQ resource from DT core

Now that all the DT drivers have switched to platform_get_irq() we can now
safely drop the static setup of IRQ resource from DT core code.

With the above change hierarchical setup of irq domains is no longer
bypassed and thus allowing hierarchical interrupt domains to describe
interrupts using "interrupts" DT property.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220316200633.28974-1-prabhakar.mahadev-lad.rj@bp.renesas.com