dm: core: Select device tree control correctly for SPL

Some boards will not use device tree for SPL even with driver model. Add
the logic to support this.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/fdtdec.h

@@ -41,6 +41,16 @@ struct fdt_memory {
 	fdt_addr_t end;
 };
 
+#ifdef CONFIG_OF_CONTROL
+# if defined(CONFIG_SPL_BUILD) && defined(SPL_DISABLE_OF_CONTROL)
+#  define OF_CONTROL 0
+# else
+#  define OF_CONTROL 1
+# endif
+#else
+# define OF_CONTROL 0
+#endif
+
 /*
  * Information about a resource. start is the first address of the resource
  * and end is the last address (inclusive). The length of the resource will