dm: core: Avoid void * in the of-platdata structs

These pointers point to drivers. Update the definition to make this clear.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/dt-structs.h b/include/dt-structs.h
index 924d51f..eed8273 100644
--- a/include/dt-structs.h
+++ b/include/dt-structs.h
@@ -8,18 +8,20 @@
 
 /* These structures may only be used in SPL */
 #if CONFIG_IS_ENABLED(OF_PLATDATA)
+struct driver_info;
+
 struct phandle_0_arg {
-	const void *node;
+	const struct driver_info *node;
 	int arg[0];
 };
 
 struct phandle_1_arg {
-	const void *node;
+	const struct driver_info *node;
 	int arg[1];
 };
 
 struct phandle_2_arg {
-	const void *node;
+	const struct driver_info *node;
 	int arg[2];
 };
 #include <generated/dt-structs-gen.h>