There is no need to track both F_BGPD and F_KERNEL anymore.

There is no need to track both F_BGPD and F_KERNEL anymore.
Remove F_KERNEL and replace the checks using the F_BGPD flag.
Also do not convert the priority in kr_tofull() instead provide
kr_priority() which does this and is used by the bgpctl imsg
commands. Also in dispatch_rtmsg_addr() convert to RTP_MINE if
the priority is equal to the configured priority.
OK tb@