KVM: arm64: vgic: Remove duplicate check in update_affinity_collection()

The 'coll' parameter to update_affinity_collection() is never NULL,
so comparing it with 'ite->collection' is enough to cover both
the NULL case and the "another collection" case.

Remove the duplicate check in update_affinity_collection().

Signed-off-by: Gavin Shan <gshan@redhat.com>
[maz: repainted commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220923065447.323445-1-gshan@redhat.com