teamd: introduce teamd_port_enabled() helper and use it

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
teamd: lw arp: rename option "always_active" to "send_always"

"active" might be confused with "active port" -> rename it.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
teamd: lw arp: allow to turn on/off validating on active/inactive ports separately

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
man: add default values for init_wait and send_always options

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
teamd: lw arp: make validation less strict so arp requests are accepted as well

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