KVM: arm/arm64: Disallow userspace control of in-kernel IRQ lines

When injecting an IRQ to the VGIC, you now have to present an owner
token for that IRQ line to show that you are the owner of that line.

IRQ lines driven from userspace or via an irqfd do not have an owner and
will simply pass a NULL pointer.

Also get rid of the unused kvm_vgic_inject_mapped_irq prototype.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>