KVM: arm64: Spin off release helper from vgic_put_irq()

KVM: arm64: Spin off release helper from vgic_put_irq()

Spin off the release implementation from vgic_put_irq() to prepare for a
more involved fix for lock ordering such that it may be unnested from
raw spinlocks. This has the minor functional change of doing call_rcu()
behind the xa_lock although it shouldn't be consequential.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250905100531.282980-4-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>