Revert "fuse: implement i_op->atomic_open()"

This reverts commit 80d5dd6387c2a9eaf81df964e2bab16d740b6698.
Revert "fuse: invalidate inode mapping if mtime changes"

This reverts commit ce56eb3823744113fb9ae7c1eadb7f4a4c1417ca.
Revert "fuse: update attributes on aio_read"

This reverts commit c3d8648e50e38ff5eaba27dde1ec229053080214.