staging/lustre: Remove now obsolete memory tracking sysctls

In the past when Lustre did its own allocation amounts tracking
the results were shown in sysctl as current and overall max
number of bytes and pages allocated. Now that we don't
track these, remove the sysctls.

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>