Staging: lustre: Fix checkpatch error: Unnecessary comparison

Removed unnecessary comparison against NULL to remove following
checkpatch error:

ERROR: spaces required around that '!='

Signed-off-by: Tina Johnson <tinajohnson.1234@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>