staging: lustre: fix integer as NULL pointer warnings

Fix several sparse warnings "Using plain integer as NULL pointer"

Signed-off-by: Alexandr Terekhov <a.terekhov@gmail.com>

 drivers/staging/lustre/lustre/ldlm/ldlm_resource.c | 4 ++--
 drivers/staging/lustre/lustre/obdclass/obd_mount.c | 4 ++--
 drivers/staging/lustre/lustre/obdecho/lproc_echo.c | 4 ++--
 drivers/staging/lustre/lustre/osc/osc_dev.c        | 2 +-
 drivers/staging/lustre/lustre/ptlrpc/import.c      | 2 +-
 5 files changed, 8 insertions(+), 8 deletions(-)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>