fix(plat/st): correct BSEC error code management

BSEC services should return SMC error codes as other IDs (defined in
stm32mp1_smc.h) and not BSEC driver ones. So that non-secure caller
is able to treat them correctly.

In global SMC handler, unknown ID should also return a value from this
definition list, and not the generic one, which seems not well adapted
for our needs.

Two unsigned values initializations are also changed from 0 to 0U.

Change-Id: Ib6fd3866a748cefad1d13d48f7be38241621023e
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
diff --git a/plat/st/stm32mp1/include/stm32mp1_smc.h b/plat/st/stm32mp1/include/stm32mp1_smc.h
index 57240bc..52088de 100644
--- a/plat/st/stm32mp1/include/stm32mp1_smc.h
+++ b/plat/st/stm32mp1/include/stm32mp1_smc.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2019, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2016-2021, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -58,4 +58,10 @@
 #define STM32_SMC_WRITE_SHADOW		0x03
 #define STM32_SMC_READ_OTP		0x04
 
+/* SMC error codes */
+#define STM32_SMC_OK			0x00000000U
+#define STM32_SMC_NOT_SUPPORTED		0xFFFFFFFFU
+#define STM32_SMC_FAILED		0xFFFFFFFEU
+#define STM32_SMC_INVALID_PARAMS	0xFFFFFFFDU
+
 #endif /* STM32MP1_SMC_H */