fix get_ha_sync_data_for_host for non-dvr agent

fix get_ha_sync_data_for_host for non-dvr agent

get_ha_sync_data_for_host will call _get_dvr_sync_data
even given agent is not in DVR agent_mode.
_get_dvr_sync_data has additional processing for dvr
like:
    dvr_router_ids = set(router['id'] for router in routers
                         if is_distributed_router(router))
    floating_ip_port_ids = [fip['port_id'] for fip in floating_ips
                                if fip['router_id'] in dvr_router_ids]
which should only work for DVR scenario.

That will increase neutron-server processing time for
non-DVR scenario. Adding logic to judge whether given
agent is in DVR agent_mode, call get_sync_data directly.

Closes-Bug: #1510796
Change-Id: I5572e19b7cd8b2ea63fde4463705ab1c56fe5e68