On discovery stage add set of TargetAddress keys to reply, reporting to
the client all the portal groups addresses and ports.

Reviewed by:	trasz@
MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
Ticket:		#5244

(cherry picked from commit d8f7f85b0adfee5dcd3f8be62aeb2ddf9846caea)