test: Add a test for regmap

We use syscon to test that the regmap functions work as expected.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/Makefile b/test/dm/Makefile
index 99cd21f..eda9643 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -23,6 +23,7 @@
 obj-$(CONFIG_DM_MMC) += mmc.o
 obj-$(CONFIG_DM_PCI) += pci.o
 obj-$(CONFIG_RAM) += ram.o
+obj-y += regmap.o
 obj-$(CONFIG_RESET) += reset.o
 obj-$(CONFIG_DM_RTC) += rtc.o
 obj-$(CONFIG_DM_SPI_FLASH) += sf.o