Revert "MIPS: Octeon: Remove special handling of CONFIG_MIPS_ELF_APPENDED_DTB=y"

This reverts commit d9df9fb9.

For the OCTEON boards, it need to patch the built-in DTB before using
it. Previously it judges if it is a built-in DTB by checking
fw_passed_dtb. But after commit 37e5c69f ("MIPS: head.S: Init
fw_passed_dtb to builtin DTB", the fw_passed_dtb is initialized even
when using built-in DTB. This causes the OCTEON boards boot broken due
to an unpatched built-in DTB is used. Revert the commit d9df9fb9 to
restore the codes before the fw_passed_dtb is used and then fix this
issue.

Fixed: 37e5c69f ("MIPS: head.S: Init fw_passed_dtb to builtin DTB")
Cc: stable@vger.kernel.org
Suggested-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/cavium-octeon/setup.c

@@ -1149,12 +1149,15 @@ void __init device_tree_init(void)
 	bool do_prune;
 	bool fill_mac;
 
-	if (fw_passed_dtb) {
-		fdt = (void *)fw_passed_dtb;
+#ifdef CONFIG_MIPS_ELF_APPENDED_DTB
+	if (!fdt_check_header(&__appended_dtb)) {
+		fdt = &__appended_dtb;
 		do_prune = false;
 		fill_mac = true;
 		pr_info("Using appended Device Tree.\n");
-	} else if (octeon_bootinfo->minor_version >= 3 && octeon_bootinfo->fdt_addr) {
+	} else
+#endif
+	if (octeon_bootinfo->minor_version >= 3 && octeon_bootinfo->fdt_addr) {
 		fdt = phys_to_virt(octeon_bootinfo->fdt_addr);
 		if (fdt_check_header(fdt))
 			panic("Corrupt Device Tree passed to kernel.");