irqdesc: Add function to identify percpu_devid irqs

irq_is_percpu indicates whether an irq should only target a single cpu.
PERCPU_DEVID flag indicates that an irq can be configured differently on
each cpu it can target.

Provide a function to check whether an irq is PERCPU_DEVID.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>