BassClient: Convert metadata for addSource op

Instead of realying on the scanned result, use the
passed metadata. This is needed to accept our own
broadcast metadata, as it is not visible in the
scan results.

Bug: 150670922
Sponsor: jpawlowski@
Test: tested manually
Merged-In: I156916747501e70a0b9a53dc42cefda4a5e989d0
Change-Id: I156916747501e70a0b9a53dc42cefda4a5e989d0
(cherry picked from commit 59d14194)