Add missing "struct" to in sizeof.

Lead to a compile error when the struct was no longer typedef'd.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index c856905..20402c6 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3731,7 +3731,7 @@
 		/* 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;
 	}