Simplify the handling of interrupts that require an IRQ domain
resolution:
- domains now cache the irqdata instead of the irq number
- consistent behaviour wrt RCU
- single lookup for architectures using sparse IRQs
- reduced boilerplate code in drivers.

* irq/generic_handle_domain_irq-core: (26 commits)
  irqchip: Bulk conversion to generic_handle_domain_irq()
  genirq: Move non-irqdomain handle_domain_irq() handling into ARM's handle_IRQ()
  genirq: Add generic_handle_domain_irq() helper
  irqchip/nvic: Convert from handle_IRQ() to handle_domain_irq()
  irqdesc: Fix __handle_domain_irq() comment
  genirq: Use irq_resolve_mapping() to implement __handle_domain_irq() and co
  irqdomain: Introduce irq_resolve_mapping()
  irqdomain: Protect the linear revmap with RCU
  irqdomain: Cache irq_data instead of a virq number in the revmap
  irqdomain: Use struct_size() helper when allocating irqdomain
  irqdomain: Make normal and nomap irqdomains exclusive
  powerpc: Move the use of irq_domain_add_nomap() behind a config option
  irqdomain: Reimplement irq_linear_revmap() with irq_find_mapping()
  irqdomain: Kill irq_domain_add_legacy_isa
  powerpc: Drop dependency between asm/irq.h and linux/irqdomain.h
  powerpc: Convert irq_domain_add_legacy_isa use to irq_domain_add_legacy
  scsi/ibmvscsi: Directly include linux/{of.h,irqdomain.h}
  powerpc: Add missing linux/{of.h,irqdomain.h} include directives
  MIPS: Do not include linux/irqdomain.h from asm/irq.h
  MIPS: Add missing linux/irqdomain.h includes
  ...