Fix bad sscan() -> scanf() conversion

Caused fio to stall waiting for disk updates.

Also add --debug=diskutil debug option, to trace what diskutil is doing.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/init.c b/init.c
index 7711189..8683ba6 100644
--- a/init.c
+++ b/init.c
@@ -838,6 +838,7 @@
 	{ .name = "verify",	.shift = FD_VERIFY },
 	{ .name = "random",	.shift = FD_RANDOM },
 	{ .name = "parse",	.shift = FD_PARSE },
+	{ .name = "diskutil",	.shift = FD_DISKUTIL },
 	{ },
 };