kvm-irqchip: do explicit commit when update irq

kvm-irqchip: do explicit commit when update irq

In the past, we are doing gsi route commit for each irqchip route
update. This is not efficient if we are updating lots of routes in the
same time. This patch removes the committing phase in
kvm_irqchip_update_msi_route(). Instead, we do explicit commit after all
routes updated.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>