net/colo-compare.c: Remove duplicated code

Fix duplicated code:
https://bugs.launchpad.net/qemu/+bug/1811499



Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>