scripts:project_xilinx.mk: Fix make clean-all target

Signed-off-by: AndreiGrozav <andrei.grozav@analog.com>

projects/scripts/project-xilinx.mk

@@ -89,9 +89,11 @@ clean:
 		$(HL)$(PROJECT_NAME)$(NC) project)
 	-rm -Rf ${DIR_NAME}
 
-clean-all: TARGET:=clean
-clean-all: clean $(M_DEPS)
+clean-all: clean
 	@rm -Rf $(CLEAN_DIRS)
+	@for lib in $(LIB_DEPS); do \
+		$(MAKE) -C $(HDL_LIBRARY_PATH)$${lib} clean; \
+	done
 
 MODE ?= "default"