Refactor makefile a bit

Makefile

@@ -52,14 +52,14 @@ ch32%:
 	@echo "Fetching $@"
 	@curl $(CURL_FLAGS) $(BASE)/$@
 
-$(TARGET).bin : $(TARGET).elf
-	@$(OBJCOPY) -O binary $< $(TARGET).bin
+%.bin : %.elf
+	$(OBJCOPY) -O binary $< $@
 
-$(TARGET).lst : $(TARGET).elf
-	@$(OBJDUMP) -S $^ > $(TARGET).lst
+%.lst : %.elf
+	$(OBJDUMP) -S $^ > $@
 
-$(TARGET).hex : $(TARGET).elf
-	@$(OBJCOPY) -O ihex $< $(TARGET).hex
+%.hex : %.elf
+	$(OBJCOPY) -O ihex $< $@
 
 flash: $(TARGET).bin
 	minichlink -w $(TARGET).bin flash -b