event: Add a simple test

Add a test for event registration and activation.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/common/Makefile b/test/common/Makefile
index 24c9145..9087788 100644
--- a/test/common/Makefile
+++ b/test/common/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0+
 obj-y += cmd_ut_common.o
 obj-$(CONFIG_AUTOBOOT) += test_autoboot.o
+obj-$(CONFIG_EVENT) += event.o