staging: lustre: fix GLOBAL_INITIALISERS checkpatch.pl errors

Fix occurencies of the following checkpatch.pl error:
ERROR: do not initialise globals to 0 or NULL

Signed-off-by: Mike Rapoport <mike.rapoport@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>