kernel/sysctl.c: fix sizeof argument to match variable name

Fix sizeof argument to be the same as the data variable name.  Probably
a copy/paste error.

Mostly harmless since both variables are unsigned int.

Fixes kernel bugzilla #197371:
  Possible access to unintended variable in "kernel/sysctl.c" line 1339
https://bugzilla.kernel.org/show_bug.cgi?id=197371

Link: http://lkml.kernel.org/r/e0d0531f-361e-ef5f-8499-32743ba907e1@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Petru Mihancea <petrum@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sysctl.c

@@ -1340,7 +1340,7 @@ static struct ctl_table vm_table[] = {
 	{
 		.procname	= "dirtytime_expire_seconds",
 		.data		= &dirtytime_expire_interval,
-		.maxlen		= sizeof(dirty_expire_interval),
+		.maxlen		= sizeof(dirtytime_expire_interval),
 		.mode		= 0644,
 		.proc_handler	= dirtytime_interval_handler,
 		.extra1		= &zero,