bts: fix osmo-bts.cfg: change osmux local-ip 127.0.0.{1->11}

When running ttcn3-bts-test natively (without Docker), the osmux
related testcases TC_speech_osmux_tch[fh] fail because both osmo-bts
and the testsuite are configured to bind() at '127.0.0.1:1984'.

Change-Id: I768933c83ae9dd2cd65eed955b2f823b6421cc4c
1 file changed