Revert "vhost-vdpa: fix page pinning leakage in error path"

This reverts commit 7ed9e3d9.

The patch creates a DoS risk since it can result in a high order memory
allocation.

Fixes: 7ed9e3d9 ("vhost-vdpa: fix page pinning leakage in error path")
Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>