init: --minimal does not take an optional argument

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/init.c b/init.c
index cc35e2b..05c73ef 100644
--- a/init.c
+++ b/init.c
@@ -100,7 +100,7 @@
 	},
 	{
 		.name		= (char *) "minimal",
-		.has_arg	= optional_argument,
+		.has_arg	= no_argument,
 		.val		= 'm' | FIO_CLIENT_FLAG,
 	},
 	{