genirq: Allow the PM device to originate from irq domain

As a preparation to moving the reference to the device used for
runtime power management, add a new 'dev' field to the irqdomain
structure for that exact purpose.

The irq_chip_pm_{get,put}() helpers are made aware of the dual
location via a new private helper.

No functional change intended.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Tony Lindgren <tony@atomide.com>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Link: https://lore.kernel.org/r/20220201120310.878267-2-maz@kernel.org