irqchip/gic-v3: Move irq_domain_update_bus_token to after checking for NULL domain

irq_domain_update_bus_token should be called after checking for NULL
domain.

Signed-off-by: Liguang Zhang <zhangliguang@linux.alibaba.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1583983255-44115-1-git-send-email-zhangliguang@linux.alibaba.com