net/colo-compare.c: Introduce parameter for compare_chr_send()

This patch change the compare_chr_send() parameter from CharBackend to CompareState,
we can get more information like vnet_hdr(We use it to support packet with vnet_header).

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>