soc: gd32vf103: Link soc-specific before common code

For a proper initialisation,  the soc-specific `__nuclei_start` has to
be executed before the common `__start`. To ensure that `__nuclei_start`
is linked first, I added the linker section init.

Signed-off-by: Greter Raffael <rgreter@baumer.com>

soc/riscv/gd_gd32/gd32vf103/CMakeLists.txt

@@ -4,4 +4,6 @@
 zephyr_sources(entry.S)
 zephyr_sources(soc.c)
 
+zephyr_linker_sources(ROM_START SORT_KEY 0x0 init.ld)
+
 set(SOC_LINKER_SCRIPT ${ZEPHYR_BASE}/include/zephyr/arch/riscv/common/linker.ld CACHE INTERNAL "")

soc/riscv/gd_gd32/gd32vf103/entry.S

@@ -10,7 +10,7 @@
 #include <zephyr/arch/riscv/csr.h>
 
 GTEXT(__nuclei_start)
-SECTION_FUNC(vectors, __nuclei_start)
+SECTION_FUNC(init, __nuclei_start)
 	/* Disable Global Interrupt */
 	csrc mstatus, MSTATUS_MIE
 	/* Jump to logical address first to ensure correct operation of RAM region  */

soc/riscv/gd_gd32/gd32vf103/init.ld

@@ -0,0 +1,7 @@
+/*
+ * Copyright (c) 2023 Andes Technology Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+KEEP(*(.init.*))