kmemleak: change /sys/kernel/debug/kmemleak permissions from 0444 to 0644

Kmemleak can be tweaked at runtime by writing commands into debugfs
file.  Root can use it anyway, but without the write-bit this interface
isn't obvious.

Link: http://lkml.kernel.org/r/150728996582.744328.11541332857988399411.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/kmemleak.c

@@ -2104,7 +2104,7 @@ static int __init kmemleak_late_init(void)
 		return -ENOMEM;
 	}
 
-	dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
+	dentry = debugfs_create_file("kmemleak", 0644, NULL, NULL,
 				     &kmemleak_fops);
 	if (!dentry)
 		pr_warn("Failed to create the debugfs kmemleak file\n");