ANDROID: fuse-bpf: Invalidate if lower is unhashed

If the lower filesystem has deleted a file or folder behind our back, we
should drop it as well.

Bug: 221093504
Test: atest android.hardware.cts.CameraTest#testJpegThumbnailSize
      several times in a row
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Change-Id: Ibd92dea83a82dd7ab21269ae5d2533e4826f5fb7