net/colo-compare.c: Change the timer clock type

net/colo-compare.c: Change the timer clock type

The virtual clock only runs during the emulation. It stops
when the virtual machine is stopped.
The host clock should be used for device models that emulate accurate
real time sources. It will continue to run when the virtual machine
is suspended. COLO need to know the host time here.

Fixes: dd321ecfc2e ("colo-compare: Use IOThread to Check old packet
regularly and Process packets of the primary")

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>