video: fbdev: pxa3xx-gcu: Fix integer overflow in pxa3xx_gcu_write

In pxa3xx_gcu_write, a count parameter of type size_t is passed to words of
type int. Then, copy_from_user() may cause a heap overflow because it is used
as the third argument of copy_from_user().

Signed-off-by: Hyunwoo Kim <[e-mail]>
Signed-off-by: Helge Deller <[e-mail]>

drivers/video/fbdev/pxa3xx-gcu.c

···
 	struct pxa3xx_gcu_batch	*buffer;
 	struct pxa3xx_gcu_priv *priv = to_pxa3xx_gcu_priv(file);
 
-	int words = count / 4;
+	size_t words = count / 4;
 
 	/* Does not need to be atomic. There's a lock in user space,
 	 * but anyhow, this is just for statistics. */