stm32mp1: Link BL2, BL32 and DTB in one binary

platform.mk is updated to have compilation rules for DTB, stm32image tool,
and the concatenation of the 3 binaries.
A new linker script and an assembly file are added to manage this.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Mathieu Belou <mathieu.belou@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
diff --git a/plat/st/stm32mp1/stm32mp1.S b/plat/st/stm32mp1/stm32mp1.S
new file mode 100644
index 0000000..7255fe5
--- /dev/null
+++ b/plat/st/stm32mp1/stm32mp1.S
@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifdef BL32_BIN_PATH
+.section .bl32_image
+.incbin BL32_BIN_PATH
+#endif
+
+.section .bl2_image
+.incbin BL2_BIN_PATH
+
+.section .dtb_image
+.incbin DTB_BIN_PATH