feat(plat/st): implement platform functions for SMCCC_ARCH_SOC_ID

The JEDEC information for STMicroelectronics is:
JEDEC_ST_MFID U(0x20)
JEDEC_ST_BKID U(0x0)
And rely on platform functions to get chip IP and revision.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: I4fa4ac8bb5583b1871b768decc9fe08e8966ff54
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index 2663da0..42d3487 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -11,6 +11,9 @@
 
 #include <platform_def.h>
 
+#define JEDEC_ST_BKID U(0x0)
+#define JEDEC_ST_MFID U(0x20)
+
 /* Functions to save and get boot context address given by ROM code */
 void stm32mp_save_boot_ctx_address(uintptr_t address);
 uintptr_t stm32mp_get_boot_ctx_address(void);