of: only scan for reserved mem when fdt present

When the reserved memory patches hit -next, several legacy (non-DT) boot
failures were detected and bisected down to that commit. There needs to
be some sanity checking whether a DT is even present before parsing the
reserved ranges.
Reported-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/fdt.c

@@ -557,6 +557,9 @@ static int __init __fdt_scan_reserved_mem(unsigned long node, const char *uname,
  */
 void __init early_init_fdt_scan_reserved_mem(void)
 {
+	if (!initial_boot_params)
+		return;
+
 	of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
 	fdt_init_reserved_mem();
 }