dm integrity: fix missing goto in bitmap_flush_interval error handling

commit 17e9e134 upstream.

Fixes: 468dfca3 ("dm integrity: add a bitmap mode")
Cc: stable@vger.kernel.org
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>