test: Add AXI test

Add tests for the AXI uclass.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/test/dm/Makefile b/test/dm/Makefile
index d2ed96c..564e846 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -44,4 +44,5 @@
 obj-$(CONFIG_ADC) += adc.o
 obj-$(CONFIG_SPMI) += spmi.o
 obj-$(CONFIG_WDT) += wdt.o
+obj-$(CONFIG_AXI) += axi.o
 endif