chan_sip: Peers with distinct source ports don't match, regardless of transport.

Previously, peers connected via TCP (or TLS) were matched by ignoring their
source port. One cannot say anything when protocol:IP:port match, yes (see
<http://stackoverflow.com/q/3329641>). However, when the ports do not match, the
peers do not match as well.

This change allows two peers connected to an Asterisk server via TCP (or TLS)
behind a NAT (= same source IP address) to be differentiated via their port as
well.

ASTERISK-27457
Reported by: Stephane Chazelas

Change-Id: Id190428bf1d931f2dbfd4b293f53ff8f20d98efa