Revert "drm/shmem-helper: Pass GEM shmem object in public interfaces"

This reverts commit ff0087df which is
commit a193f3b4 upstream.

It causes an ABI break in Android kernels by removing a symbol that many
DRM drivers use.  There is no real need for it in the stable tree at
this point in time, so just revert it as it's not needed.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1a50f8b70bf8d9ccb408e3acf0fb24180e7ec79b