staging: ramster: disable build in anticipation of renaming

[V2: no code changes, patchset now generated via git format-patch -M]

In staging, disable ramster build in anticipation of renaming to zcache

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>