tools: ynl: use ynl-gen -o instead of stdout in Makefile

Jiri added more careful handling of output of the code generator
to avoid wiping out existing files in
commit f65f305 ("tools: ynl-gen: use temporary file for rendering")
Make use of the -o option in the Makefiles, it is already used
by ynl-regen.sh.

Link: https://lore.kernel.org/r/20231010202714.4045168-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/generated/Makefile

@@ -27,11 +27,11 @@ protos.a: $(OBJS)
 
 %-user.h: ../../../../Documentation/netlink/specs/%.yaml $(TOOL)
 	@echo -e "\tGEN $@"
-	@$(TOOL) --mode user --header --spec $< $(YNL_GEN_ARG_$*) > $@
+	@$(TOOL) --mode user --header --spec $< -o $@ $(YNL_GEN_ARG_$*)
 
 %-user.c: ../../../../Documentation/netlink/specs/%.yaml $(TOOL)
 	@echo -e "\tGEN $@"
-	@$(TOOL) --mode user --source --spec $< $(YNL_GEN_ARG_$*) > $@
+	@$(TOOL) --mode user --source --spec $< -o $@ $(YNL_GEN_ARG_$*)
 
 %-user.o: %-user.c %-user.h
 	@echo -e "\tCC $@"