dm: blk: Add tests for block devices

Add some tests to check that block devices work as expected.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/test/dm/Makefile b/test/dm/Makefile
index fd0198f..df2d71f 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -15,6 +15,7 @@
 # subsystem you must add sandbox tests here.
 obj-$(CONFIG_UT_DM) += core.o
 ifneq ($(CONFIG_SANDBOX),)
+obj-$(CONFIG_BLK) += blk.o
 obj-$(CONFIG_CLK) += clk.o
 obj-$(CONFIG_DM_ETH) += eth.o
 obj-$(CONFIG_DM_GPIO) += gpio.o