chan_sip: Remove excess ref of realtime peer before sip_poke_peer.

The peer is referenced at the end of sip_poke_peer, it should not get
an extra ref before the call to sip_poke_peer. This fixes a memory
leak.

ASTERISK-22945 #close
Reported by: ibercom
Tested by: Yuriy Gorlichenko
Patches:
  asterisk11.patch uploaded by ibercom (License #6599)

Review: https://reviewboard.asterisk.org/r/4031/
........

Merged revisions 424176 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@424177 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -31209,7 +31209,6 @@ static struct sip_peer *build_peer(const char *name, struct ast_variable *v, str
 
 		/* Startup regular pokes */
 		if (!devstate_only && enablepoke) {
-			sip_ref_peer(peer, "schedule qualify");
 			sip_poke_peer(peer, 0);
 		}
 	}