MIPS: vmlinux: create a section for appended DTB

For bootloaders that support booting only ELF kernels and load only ELF
segments to memory there is no easy way to supply DTB without kernel
recompilation. For that purpose, create a section called .appended_dtb
that can be later updated with board-specific DTB using binutils e.g. at
kernel installation time.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11114/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/vmlinux.lds.S

@@ -132,6 +132,11 @@ SECTIONS
 	__appended_dtb = .;
 	/* leave space for appended DTB */
 	. += 0x100000;
+#elif defined(CONFIG_MIPS_ELF_APPENDED_DTB)
+	.appended_dtb : AT(ADDR(.appended_dtb) - LOAD_OFFSET) {
+		*(.appended_dtb)
+		KEEP(*(.appended_dtb))
+	}
 #endif
 	/*
 	 * Align to 64K in attempt to eliminate holes before the