bluez5: limit CVSD block size

Don't try to write data in too large blocks.

This controls the maximum amount of data to send at once. sco-io will
buffer and fragment packets to the right size.

Previously in sco-sink, SO_SNDBUF was not set, so there could be a
longer queue in the socket.

spa/plugins/bluez5/hfp-codec-cvsd.c

@@ -88,7 +88,7 @@ static void *codec_init(const struct media_codec *codec, uint32_t flags,
 	if (!this)
 		return NULL;
 
-	this->block_size = 2 * (mtu/2);
+	this->block_size = SPA_MIN(2 * (mtu/2), 144u);	/* cap to 9 ms */
 	return this;
 }