diff-no-index: do not take a redundant prefix argument

Prefix is already set up in "revs". The same prefix should be used for
all options parsing. So kill the last argument. This patch does not
actually change anything because the only caller does use the same
prefix for init_revisions() and diff_no_index().

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/diff.c b/builtin/diff.c
index 4326fa5..7b9917b 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -341,7 +341,7 @@
 	}
 	if (no_index)
 		/* If this is a no-index diff, just run it and exit there. */
-		diff_no_index(&rev, argc, argv, prefix);
+		diff_no_index(&rev, argc, argv);
 
 	/* Otherwise, we are doing the usual "git" diff */
 	rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;