dm: core: Create a struct for device runtime info

At present when driver model needs to change a device it simply updates
the struct udevice structure. But with of-platdata-inst most of the fields
are not modified at runtime. In fact, typically only the flags need to
change.

For systems running SPL from read-only memory it is convenient to separate
out the runtime information, so that the devices don't need to be copied
before being used.

Create a new udevice_rt table, similar to the existing driver_rt. For now
it just holds the flags, although they are not used in this patch.

Add a new Kconfig for the driver_rt data, since this is not needed when
of-platdata-inst is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/of_platdata.c b/test/dm/of_platdata.c
index f2b45b9..0f89c7a 100644
--- a/test/dm/of_platdata.c
+++ b/test/dm/of_platdata.c
@@ -147,7 +147,7 @@
 	uint i;
 
 	/* Skip this test if there is no platform data */
-	if (CONFIG_IS_ENABLED(OF_PLATDATA_INST))
+	if (!CONFIG_IS_ENABLED(OF_PLATDATA_DRIVER_RT))
 		return 0;
 
 	/* Record the indexes that are found */