This parameter need compare with the return of qemu_clock_get_ms(),
it is uint64_t. So we need fix this issue here.

Fixes: 9cc43c94 ("net/colo-compare.c: Expose "compare_timeout" to users")

Reported-by: Derek Su <dereksu@qnap.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>