ASoC: Unmap lab buffer during listen session close

Ensure lab buffer de-alloc even if listen session
is not in start state to avoid memory leak
when multiple listen clients are created.

Change-Id: Id6d8b37a3dcdf49618ae2a4d80903d429393cd8e
Signed-off-by: Soumya Managoli <quic_c_smanag@quicinc.com>