dm: fix design.rst document

The patch fixes some errors.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/doc/driver-model/design.rst b/doc/driver-model/design.rst
index 8fd28c0..5247ecc 100644
--- a/doc/driver-model/design.rst
+++ b/doc/driver-model/design.rst
@@ -231,7 +231,7 @@
 What is going on?
 -----------------
 
-Let's start at the top. The demo command is in common/cmd_demo.c. It does
+Let's start at the top. The demo command is in cmd/demo.c. It does
 the usual command processing and then:
 
 .. code-block:: c
@@ -402,7 +402,7 @@
 
 .. code-block:: c
 
-	static const struct dm_demo_cdata red_square = {
+	static const struct dm_demo_pdata red_square = {
 		.colour = "red",
 		.sides = 4.
 	};
@@ -489,12 +489,12 @@
 
 .. code-block:: c
 
-	U_BOOT_CLASS(demo) = {
+	UCLASS_DRIVER(demo) = {
 		.id		= UCLASS_DEMO,
 	};
 
 It is also possible to specify special methods for probe, etc. The uclass
-numbering comes from include/dm/uclass.h. To add a new uclass, add to the
+numbering comes from include/dm/uclass-id.h. To add a new uclass, add to the
 end of the enum there, then declare your uclass as above.