pq_alsa.c: fix memory leak after pq_cb_alsa_exit()

Abusing the talloc hierarchical nature may cause some problems,
e.g. on embedded systems with emulated talloc API. Let's release
the memory allocated for a state explicitly.

Change-Id: Ie675a92b1e52a4886dc447af19f65ff5e12a4c40
1 file changed