dm: memory: Introduce new uclass

Introduce UCLASS_MEMORY for future Memory Controller
device drivers.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/Makefile b/test/dm/Makefile
index 499e769..fd7d310 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -57,6 +57,7 @@
 obj-$(CONFIG_DM_MAILBOX) += mailbox.o
 obj-$(CONFIG_DM_MDIO) += mdio.o
 obj-$(CONFIG_DM_MDIO_MUX) += mdio_mux.o
+obj-$(CONFIG_MEMORY) += memory.o
 obj-$(CONFIG_MISC) += misc.o
 obj-$(CONFIG_DM_MMC) += mmc.o
 obj-$(CONFIG_CMD_MUX) += mux-cmd.o