of: Use proper types for checking memory overflow

Commit a67a6ed155
(of: Check for phys_addr_t overflows in early_init_dt_add_memory_arch)
corrected early_init_dt_add_memory_arch to account for overflows
but did so in an unclean way using ULONG_MAX. There is no
guarantee that sizeof(unsigned long) == sizeof(phys_addr_t).
Check against phys_addr_t instead.

Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/fdt.c

@@ -875,24 +875,24 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 }
 
 #ifdef CONFIG_HAVE_MEMBLOCK
+#define MAX_PHYS_ADDR	((phys_addr_t)~0)
+
 void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 {
 	const u64 phys_offset = __pa(PAGE_OFFSET);
 	base &= PAGE_MASK;
 	size &= PAGE_MASK;
 
-	if (sizeof(phys_addr_t) < sizeof(u64)) {
-		if (base > ULONG_MAX) {
+	if (base > MAX_PHYS_ADDR) {
 		pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
 				base, base + size);
 		return;
 	}
 
-		if (base + size > ULONG_MAX) {
+	if (base + size > MAX_PHYS_ADDR) {
 		pr_warning("Ignoring memory range 0x%lx - 0x%llx\n",
 				ULONG_MAX, base + size);
-			size = ULONG_MAX - base;
-		}
+		size = MAX_PHYS_ADDR - base;
 	}
 
 	if (base + size < phys_offset) {