Revert "device-tests: As a dependency to tests"

This reverts commit f153603cccbdef9821898759aee4d634f402acf3.

Change-Id: Ib439e2351da6c5eabcf412b29c6d798d05e01612
diff --git a/core/tasks/device-tests.mk b/core/tasks/device-tests.mk
index cba83cb..731937f 100644
--- a/core/tasks/device-tests.mk
+++ b/core/tasks/device-tests.mk
@@ -25,5 +25,3 @@
 
 device-tests: $(device-tests-zip)
 $(call dist-for-goals, device-tests, $(device-tests-zip))
-
-tests: device-tests