On MIPS, the only user of handle_domain_irq() is octeon_irq_ciu3_ip2(),
which is called from the platform-specific plat_irq_dispatch() function
invoked from the early assembly code.

No other irqchip relevant to arch/mips uses handle_domain_irq():

* No other plat_irq_dispatch() function transitively calls
  handle_domain_irq().

* No other vectored IRQ dispatch function registered with
  set_vi_handler() calls handle_domain_irq().

* No chained irqchip handlers call handle_domain_irq(), which makes
  sense as this is meant to only be used by root irqchip handlers.

Currently octeon_irq_ciu3_ip2() passes NULL as the `regs` argument to
handle_domain_irq(), and as handle_domain_irq() will pass this to
set_irq_regs(), any invoked IRQ handlers will erroneously see a NULL
pt_regs if they call get_pt_regs().

Fix this by calling generic_handle_domain_irq() directly, and performing
the necessary irq_{enter,exit}() logic directly in
octeon_irq_ciu3_ip2(). At the same time, deselect HANDLE_DOMAIN_IRQ,
which subsequent patches will remove.

Other than the corrected behaviour of get_pt_regs(), there should be no
functional change as a result of this patch.

Fixes: ce210d35 ("MIPS: OCTEON: Add support for OCTEON III interrupt controller.")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>