fuse: add inode/permission checks to fileattr_get/fileattr_set

It looks like these checks were accidentally lost during the conversion to
fileattr API.

Fixes: 72227eac ("fuse: convert to fileattr")
Cc: <stable@vger.kernel.org> # v5.13
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>