thunderbolt: Use the actual buffer in tb_async_error()

The received notification packet is held in pkg->buffer and not in pkg
itself. Fix this by using the correct buffer.

Fixes: 81a54b5e19 ("thunderbolt: Let the connection manager handle all notifications")
Cc: stable@vger.kernel.org
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/ctl.c

@@ -407,7 +407,7 @@ static void tb_ctl_rx_submit(struct ctl_pkg *pkg)
 
 static int tb_async_error(const struct ctl_pkg *pkg)
 {
-	const struct cfg_error_pkg *error = (const struct cfg_error_pkg *)pkg;
+	const struct cfg_error_pkg *error = pkg->buffer;
 
 	if (pkg->frame.eof != TB_CFG_PKG_ERROR)
 		return false;