Makefile: Clean up the condition for RECOVERY_RESOURCE_ZIP.

Change-Id: I6909d4572bd54da48f7fd6b76d4a5ee03c84206c
diff --git a/core/Makefile b/core/Makefile
index 19b70a8..365ea2e 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -982,7 +982,7 @@
 		$(RECOVERY_INSTALL_OTA_KEYS)
 		$(call build-recoveryimage-target, $@)
 
-ifeq (,$(filter true, $(BOARD_USES_FULL_RECOVERY_IMAGE) $(BOARD_USES_RECOVERY_AS_BOOT)))
+ifdef RECOVERY_RESOURCE_ZIP
 $(RECOVERY_RESOURCE_ZIP): $(INSTALLED_RECOVERYIMAGE_TARGET) | $(ZIPTIME)
 	$(hide) mkdir -p $(dir $@)
 	$(hide) find $(TARGET_RECOVERY_ROOT_OUT)/res -type f | sort | zip -0qrjX $@ -@