fix(fdts stm32mp1): correct copyright dates

Add 2021 year in the file header Copyright line.

Change-Id: I09f7bef1f746c429ff308286169354e58648a1cd
Signed-off-by: Yann Gautier <yann.gautier@st.com>
diff --git a/fdts/stm32mp151.dtsi b/fdts/stm32mp151.dtsi
index 3beabbb..ca93f0c 100644
--- a/fdts/stm32mp151.dtsi
+++ b/fdts/stm32mp151.dtsi
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
 /*
- * Copyright (C) STMicroelectronics 2017 - All Rights Reserved
+ * Copyright (c) 2017-2021, STMicroelectronics - All Rights Reserved
  * Author: Ludovic Barre <ludovic.barre@st.com> for STMicroelectronics.
  */
 #include <dt-bindings/interrupt-controller/arm-gic.h>