LU-6142 ptlrpc: Fix style issues for sec_null.c

LU-6142 ptlrpc: Fix style issues for sec_null.c

This patch fixes issues reported by checkpatch
for file lustre/ptlrpc/sec_null.c

Test-Parameters: trivial
Signed-off-by: Arshad Hussain <arshad.super@gmail.com>
Change-Id: I67631d35ae4461ca92516975ab71f69d01378e19
Reviewed-on: https://review.whamcloud.com/34549
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>