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

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

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

Test-Parameters: trivial
Signed-off-by: Arshad Hussain <arshad.super@gmail.com>
Change-Id: I033db1a7ee23042cc3ec0dedced48830e00d1230
Reviewed-on: https://review.whamcloud.com/35433
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>
Reviewed-by: Oleg Drokin <green@whamcloud.com>