video: pxa3xx-gcu: Return -EFAULT when copy_from_user() fails

Return -EFAULT instead of number of bytes that could not be copied if
copy_from_user() fails.

Also fix a typo in the comments.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/video/pxa3xx-gcu.c

@@ -1,5 +1,5 @@
 /*
- *  pxa3xx-gc.c - Linux kernel module for PXA3xx graphics controllers
+ *  pxa3xx-gcu.c - Linux kernel module for PXA3xx graphics controllers
  *
  *  This driver needs a DirectFB counterpart in user space, communication
  *  is handled via mmap()ed memory areas and an ioctl.
@@ -421,7 +421,7 @@ pxa3xx_gcu_misc_write(struct file *filp, const char *buff,
 		buffer->next = priv->free;
 		priv->free = buffer;
 		spin_unlock_irqrestore(&priv->spinlock, flags);
-		return ret;
+		return -EFAULT;
 	}
 
 	buffer->length = words;