fix(stm32mp1): add missing debug.h

Due to stm32mp_shres_helpers.h removal, the debug.h header is no more
included. It should then be added to stm32mp1_boot_device.c.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I397911ac05fdff464c010cf3b2e04320a781b4aa
diff --git a/plat/st/stm32mp1/stm32mp1_boot_device.c b/plat/st/stm32mp1/stm32mp1_boot_device.c
index 997335d..6a05707 100644
--- a/plat/st/stm32mp1/stm32mp1_boot_device.c
+++ b/plat/st/stm32mp1/stm32mp1_boot_device.c
@@ -1,11 +1,12 @@
 /*
- * Copyright (c) 2019, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2019-2022, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
 #include <errno.h>
 
+#include <common/debug.h>
 #include <drivers/nand.h>
 #include <drivers/raw_nand.h>
 #include <drivers/spi_nand.h>