RISC-V: Remove mem_end command line processing

This is just some cruft left over from before the port converted to
device tree.  The right way to handle memory regions is to specify them
in the device tree, which BBL (our simplest bootloader) is already
capable of doing.  This patch simply removes the cruft.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/setup.c

@@ -149,25 +149,6 @@ void __init sbi_save(unsigned int hartid, void *dtb)
 	early_init_dt_scan(__va(dtb));
 }
 
-/*
- * Allow the user to manually add a memory region (in case DTS is broken);
- * "mem_end=nn[KkMmGg]"
- */
-static int __init mem_end_override(char *p)
-{
-	resource_size_t base, end;
-
-	if (!p)
-		return -EINVAL;
-	base = (uintptr_t) __pa(PAGE_OFFSET);
-	end = memparse(p, &p) & PMD_MASK;
-	if (end == 0)
-		return -EINVAL;
-	memblock_add(base, end - base);
-	return 0;
-}
-early_param("mem_end", mem_end_override);
-
 static void __init setup_bootmem(void)
 {
 	struct memblock_region *reg;