genirq: Refactor accessors to use irq_data_get_affinity_mask

A couple of functions directly reference the affinity mask. Route them
through irq_data_get_affinity_mask so they will pick up any refactoring
done there.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220701200056.46555-6-samuel@sholland.org