Remove the restriction that PHONY_PACKAGE needs LOCAL_REQUIRED_MODULES

Change-Id: I33e776ea80368e0f0290169e680689a680186ed6
diff --git a/core/phony_package.mk b/core/phony_package.mk
index 3644db8..70b6aac 100644
--- a/core/phony_package.mk
+++ b/core/phony_package.mk
@@ -2,10 +2,6 @@
 $(error LOCAL_SRC_FILES are not allowed for phony packages)
 endif
 
-ifeq ($(strip $(LOCAL_REQUIRED_MODULES)),)
-$(error LOCAL_REQUIRED_MODULES is required for phony packages)
-endif
-
 LOCAL_MODULE_CLASS := FAKE
 LOCAL_MODULE_SUFFIX := -timestamp