staging: lustre: lustre: fix all less than 0 comparison for unsigned values

staging: lustre: lustre: fix all less than 0 comparison for unsigned values

Remove all test of less than zero for unsigned values
found with -Wtype-limits.

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8843
Reviewed-on: https://review.whamcloud.com/23811
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>