linker: allow SoC to insert linker script fragments

This allows the SoC to specify some additional linker script
fragments into the bss, data and read-only data sections.

For example, the Cypress PSOC6 has a few input sections that
must be put into bss and data sections. Without specifying
these in the linker script, they are consider orphan sections
and the placement is based on linker heuristic which is
arbitrary.

POSIX is not supported as the main linker script is
provided by the host system's binutils and we have no control
over it. Also, currently Xtensa SoCs have their own linker
scripts so there is no need to this feature.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

soc/Kconfig

@@ -16,3 +16,39 @@ module-str = SOC
 source "subsys/logging/Kconfig.template.log_config"
 
 endmenu
+
+#
+# SOC_*_LD: SoC specific Linker script additions
+#
+config SOC_NOINIT_LD
+	bool
+	depends on (ARC || ARM || X86 || NIOS2 || RISCV32)
+	help
+	  Include an SoC specific linker script fragment named soc-noinit.ld
+	  for inserting additional data and linker directives into
+	  the noinit section.
+
+	  This only has effect if the SoC uses the common linker script
+	  under include/arch/.
+
+config SOC_RODATA_LD
+	bool
+	depends on (ARC || ARM || X86 || NIOS2 || RISCV32)
+	help
+	  Include an SoC specific linker script fragment named soc-rodata.ld
+	  for inserting additional data and linker directives into
+	  the rodata section.
+
+	  This only has effect if the SoC uses the common linker script
+	  under include/arch/.
+
+config SOC_RWDATA_LD
+	bool
+	depends on (ARC || ARM || X86 || NIOS2 || RISCV32)
+	help
+	  Include an SoC specific linker script fragment named soc-rwdata.ld
+	  for inserting additional data and linker directives into
+	  the data section.
+
+	  This only has effect if the SoC uses the common linker script
+	  under include/arch/.