irqchip/gic-v3-its: Add ability to resend MAPC on resume

This adds functionality to resend the MAPC command to an ITS node on
resume. If the ITS is powered down during suspend and the collections
are not backed by memory, the ITS will lose that state. This just sets
up the known state for the collections after the ITS is restored.

Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>