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

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

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

Test-Parameters: trivial
Signed-off-by: Arshad Hussain <arshad.super@gmail.com>
Change-Id: I03220084b303d9d411665db9a6080f934115b67a
Reviewed-on: https://review.whamcloud.com/34550
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>