[PATCH] rtc subsystem: use ENOIOCTLCMD and ENOTTY where appropriate

Appropriately use -ENOIOCTLCMD and -ENOTTY when the ioctl is not
implemented by a driver.

(akpm: we're not allowed to return -ENOIOCTLCMD to userspace.  This patch does
the right thing).

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/rtc/rtc-vr41xx.c b/drivers/rtc/rtc-vr41xx.c
index 4d49fd5..277596c 100644
--- a/drivers/rtc/rtc-vr41xx.c
+++ b/drivers/rtc/rtc-vr41xx.c
@@ -270,7 +270,7 @@
 		epoch = arg;
 		break;
 	default:
-		return -EINVAL;
+		return -ENOIOCTLCMD;
 	}
 
 	return 0;