arch/tile: Add a warning if we try to allocate too much vmalloc memory.

	pte_t *pte;

	BUG_ON(pgd_addr_invalid(addr));

	if (addr < VMALLOC_START || addr >= VMALLOC_END)

		panic("PCPU addr %#lx outside vmalloc range %#lx..%#lx;"

		      " try increasing CONFIG_VMALLOC_RESERVE\n",

		      addr, VMALLOC_START, VMALLOC_END);

	pgd = swapper_pg_dir + pgd_index(addr);

	pud = pud_offset(pgd, addr);