teamd_link_watch: allow to send ARP probes if no source_host is specified

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
bond2team: do not guess source_host option

Since now teamd accepts config without "source_host" set, benefit from
that fact and do not make up some IP address here.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
teamd_link_watch: specify "missed_max" option default value

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
man: correct type of "*_host" options

Signed-off-by: Jiri Pirko <jiri@resnulli.us>