drivers: enhance check for mount fs type
drivers: enhance check for mount fs type

when checking that a mount has a specific file system type, also
validate that it is on a different than its parent directory.

This helps when using virtiofs as the underlying file system since the
check used for fuse-overlayfs would fail since they both use FUSE.

Signed-off-by: Giuseppe Scrivano <20002b7b24c75512093a71a58285826d5c504fca@redhat.com>

containers/storage,containers/storage,containers/storage