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

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

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

Test-Parameters: trivial
Signed-off-by: Arshad Hussain <arshad.super@gmail.com>
Change-Id: Ibaffcdfaeac48176ba05b5e4f4471f9db96d9cbe
Reviewed-on: https://review.whamcloud.com/34605
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: Oleg Drokin <green@whamcloud.com>