treewide: Use OF_REAL instead of !OF_PLATDATA

Now that we have a 'positive' Kconfig option, use this instead of the
negative one, which is harder to understand.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/sysreset/sysreset_sandbox.c b/drivers/sysreset/sysreset_sandbox.c
index 0868582..0ee286c 100644
--- a/drivers/sysreset/sysreset_sandbox.c
+++ b/drivers/sysreset/sysreset_sandbox.c
@@ -133,7 +133,7 @@
 	.ops		= &sandbox_warm_sysreset_ops,
 };
 
-#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+#if CONFIG_IS_ENABLED(OF_REAL)
 /* This is here in case we don't have a device tree */
 U_BOOT_DRVINFO(sysreset_sandbox_non_fdt) = {
 	.name = "sysreset_sandbox",