audio/avdtp: Fix passing wrong error code

finalize_discovery actually expect positive codes since it passes to
avdtp_error_init.
diff --git a/profiles/audio/avdtp.c b/profiles/audio/avdtp.c
index 78e7b4d..4f663d4 100644
--- a/profiles/audio/avdtp.c
+++ b/profiles/audio/avdtp.c
@@ -3481,7 +3481,7 @@
 	if (!stream && session->discover) {
 		/* Don't call cb since it being aborted */
 		session->discover->cb = NULL;
-		finalize_discovery(session, -ECANCELED);
+		finalize_discovery(session, ECANCELED);
 		return -EALREADY;
 	}