LU-6142 tests: Fix style issues for write_append_truncate.c

LU-6142 tests: Fix style issues for write_append_truncate.c

This patch fixes issues reported by checkpatch for file
lustre/tests/mpi/write_append_truncate.c

Change-Id: Iab8f0ab0e6c501f31aca8f2a58eab8fbea0c2685
Signed-off-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-on: https://review.whamcloud.com/35493
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>