integrity: fix segfault on error path when replacing images

integrity: fix segfault on error path when replacing images

When adding replacement raid+integrity images (lvconvert --repair
after a raid image is lost), various errors can cause the function
to exit with an error.  On this exit path, the function attempts
to revert new images that had been created but not yet used.  The
cleanup failed to account for the fact that not all images needed
to be reverted.