dm: core: Implement live tree 'read' functions

When the live tree is supported some functions need to change a little.
Add an implementation which is used when not inlining these functions.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/Makefile b/drivers/core/Makefile
index d74b065..435cf98 100644
--- a/drivers/core/Makefile
+++ b/drivers/core/Makefile
@@ -12,4 +12,7 @@
 obj-$(CONFIG_$(SPL_)REGMAP)	+= regmap.o
 obj-$(CONFIG_$(SPL_)SYSCON)	+= syscon-uclass.o
 obj-$(CONFIG_OF_LIVE) += of_access.o of_addr.o
+ifndef CONFIG_DM_DEV_READ_INLINE
+obj-$(CONFIG_OF_CONTROL) += read.o
+endif
 obj-$(CONFIG_OF_CONTROL) += of_extra.o ofnode.o