bsec: move bsec_mode_is_closed_device() service to platform

This BSEC service is a platform specific service. Implementation
moved to the platform part.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Change-Id: I1f70ed48a446860498ed111acce01187568538c9
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index e20308e..59657fd 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -19,6 +19,7 @@
 uintptr_t stm32mp_get_boot_ctx_address(void);
 
 bool stm32mp_is_single_core(void);
+bool stm32mp_is_closed_device(void);
 
 /* Return the base address of the DDR controller */
 uintptr_t stm32mp_ddrctrl_base(void);