Input: Break out MT data

Move all MT-related things to a separate place. This saves some
bytes for non-mt input devices, and prepares for new MT features.

Reviewed-and-tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Tested-by: Ping Cheng <pingc@wacom.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 6c58bff..a0692c5 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -653,20 +653,22 @@
 				   unsigned int size,
 				   int __user *ip)
 {
-	const struct input_mt_slot *mt = dev->mt;
+	const struct input_mt *mt = dev->mt;
 	unsigned int code;
 	int max_slots;
 	int i;
 
 	if (get_user(code, &ip[0]))
 		return -EFAULT;
-	if (!input_is_mt_value(code))
+	if (!mt || !input_is_mt_value(code))
 		return -EINVAL;
 
 	max_slots = (size - sizeof(__u32)) / sizeof(__s32);
-	for (i = 0; i < dev->mtsize && i < max_slots; i++)
-		if (put_user(input_mt_get_value(&mt[i], code), &ip[1 + i]))
+	for (i = 0; i < mt->num_slots && i < max_slots; i++) {
+		int value = input_mt_get_value(&mt->slots[i], code);
+		if (put_user(value, &ip[1 + i]))
 			return -EFAULT;
+	}
 
 	return 0;
 }