gpio: thunderx: select IRQ_DOMAIN_HIERARCHY instead of depends on
IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
selected by drivers that need IRQ domain hierarchy support.
GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
This means, we can not enable GPIO_THUNDERX unless other drivers
select IRQ_DOMAIN_HIERARCHY elsewhere. This is odd. Flip the logic.