staging: lustre: remove LPLU, LPLD, and LPLX defines

They are variable modifiers, come on, no need for a special define just
for them...

Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>