feat(stm32mp1): add logic to pass the boot index to the Update Agent

With the FWU Multi Bank update feature, the platform can boot from one
of multiple banks(partitions). Pass the value of bank from which the
platform has booted as boot index to the Update Agent. The Update
Agent will match this boot index value against the active_index field
in the metadata, and update the metadata if there is a mismatch.

Fow now, the mechanism to pass the boot index is platform specific. On
the STM32MP1 platform, the boot index value is passed through a
memorey mapped TAMP register on the SoC.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Change-Id: I0aa665ff9c1db95be8ae19ed8de6d866587d6850
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index 9ca5d16..7508004 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -113,4 +113,8 @@
 void stm32_save_boot_interface(uint32_t interface, uint32_t instance);
 void stm32_get_boot_interface(uint32_t *interface, uint32_t *instance);
 
+#if !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT
+void stm32mp1_fwu_set_boot_idx(void);
+#endif /* !STM32MP_USE_STM32IMAGE && PSA_FWU_SUPPORT */
+
 #endif /* STM32MP_COMMON_H */