feat(stm32mp1): add "Boot mode" management for STM32MP13

Add new APIs to enter and exit "boot mode".

In this mode a potential tamper won't block access or reset
the secure IPs needed while boot, without this mode a dead
lock may occurs.

Change-Id: Iad60d4a0420ec125b842a285f73a20eb54cd1828
Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@st.com>
diff --git a/plat/st/stm32mp1/include/stm32mp1_private.h b/plat/st/stm32mp1/include/stm32mp1_private.h
index 7bdb36d..23934e9 100644
--- a/plat/st/stm32mp1/include/stm32mp1_private.h
+++ b/plat/st/stm32mp1/include/stm32mp1_private.h
@@ -23,6 +23,14 @@
 void stm32mp1_syscfg_disable_io_compensation(void);
 uint32_t stm32mp1_syscfg_get_chip_version(void);
 uint32_t stm32mp1_syscfg_get_chip_dev_id(void);
+#if STM32MP13
+void stm32mp1_syscfg_boot_mode_enable(void);
+void stm32mp1_syscfg_boot_mode_disable(void);
+#endif
+#if STM32MP15
+static inline void stm32mp1_syscfg_boot_mode_enable(void){}
+static inline void stm32mp1_syscfg_boot_mode_disable(void){}
+#endif
 
 void stm32mp1_deconfigure_uart_pins(void);