cmd: Move the "dm" command from test/dm/ to cmd/

The "dm" command under CONFIG_CMD_DM should live under cmd/ rather than
test/dm/ so move it.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Makefile b/cmd/Makefile
index 4998643..15ae4d2 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -40,6 +40,7 @@
 obj-$(CONFIG_DATAFLASH_MMC_SELECT) += dataflash_mmc_mux.o
 obj-$(CONFIG_CMD_DATE) += date.o
 obj-$(CONFIG_CMD_DEMO) += demo.o
+obj-$(CONFIG_CMD_DM) += dm.o
 obj-$(CONFIG_CMD_SOUND) += sound.o
 ifdef CONFIG_POST
 obj-$(CONFIG_CMD_DIAG) += diag.o