selftests/capabilities: actually test it

The capatabilities exist in selftest but no in the TARGETS list.
Add it to the TARGETS.

Signed-off-by: Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index c8edff6..ec0ecad 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -1,4 +1,5 @@
 TARGETS = breakpoints
+TARGETS += capabilities
 TARGETS += cpu-hotplug
 TARGETS += efivarfs
 TARGETS += exec