riscv: Remove non-standard linux,elfcorehdr handling

RISC-V uses platform-specific code to locate the elf core header in
memory.  However, this does not conform to the standard
"linux,elfcorehdr" DT bindings, as it relies on a reserved memory node
with the "linux,elfcorehdr" compatible value, instead of on a
"linux,elfcorehdr" property under the "/chosen" node.

The non-compliant code can just be removed, as the standard behavior is
already implemented by platform-agnostic handling in the FDT core code.

Fixes: 5640975 ("RISC-V: Add crash kernel support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/41c75d6ee3114ae6304f8afe0051895af91200ee.1628670468.git.geert+renesas@glider.be

arch/riscv/mm/init.c

@@ -829,26 +829,6 @@ static void __init reserve_crashkernel(void)
 }
 #endif /* CONFIG_KEXEC_CORE */
 
-#ifdef CONFIG_CRASH_DUMP
-/*
- * We keep track of the ELF core header of the crashed
- * kernel with a reserved-memory region with compatible
- * string "linux,elfcorehdr". Here we register a callback
- * to populate elfcorehdr_addr/size when this region is
- * present. Note that this region will be marked as
- * reserved once we call early_init_fdt_scan_reserved_mem()
- * later on.
- */
-static int __init elfcore_hdr_setup(struct reserved_mem *rmem)
-{
-	elfcorehdr_addr = rmem->base;
-	elfcorehdr_size = rmem->size;
-	return 0;
-}
-
-RESERVEDMEM_OF_DECLARE(elfcorehdr, "linux,elfcorehdr", elfcore_hdr_setup);
-#endif
-
 void __init paging_init(void)
 {
 	setup_bootmem();