Revert "audio/audio_pt_int: Clarify licensing"

This reverts commit 72bc6f1b.

This patch wasn't submitted to the list and did not get Acked by other
copyright holders in the file.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

audio/audio_pt_int.c

-/* public domain */
 #include "qemu-common.h"
 #include "audio.h"