Regression test portability: mkdir

mkdir -v (verbose) is not portable, just remove it.

BUG: 764655
Change-Id: If344792caf977698abe0bf497d9083bc9333df55
Signed-off-by: Emmanuel Dreyfus <manu@netbsd.org>
Reviewed-on: http://review.gluster.org/8463
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Harshavardhana <harsha@harshavardhana.net>
Tested-by: Harshavardhana <harsha@harshavardhana.net>