Revert "ANDROID: vfs: add d_canonical_path for stacked filesystem support"

This reverts commit eb9e939d as there is
no need for it now that sdcardfs is gone.

Bug: 157700134
Cc: Daniel Rosenberg <drosen@google.com>
Cc: Alistair Strachan <astrachan@google.com>
Cc: Yongqin Liu <yongqin.liu@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1c05f8fe02dca6f17d374cc1cd6fffb169391391