Add missing "struct" to in sizeof.

Lead to a compile error when the struct was no longer typedef'd.
Signed-off-by: NJesper Nilsson <jesper.nilsson@axis.com>

drivers/serial/crisv10.c

@@ -3731,7 +3731,7 @@ rs_ioctl(struct tty_struct *tty, struct file * file,
 		/* This is the ioctl to get RS485 data from user-space */
 		if (copy_to_user((struct serial_rs485 *) arg,
 					rs485data,
-					sizeof(serial_rs485)))
+					sizeof(struct serial_rs485)))
 			return -EFAULT;
 		break;
 	}