tools: gpio: remove the include directory on make clean

Remove the generated include directory when running make clean.

Fixes: 8674cea84dc6 ("tools/gpio: move to tools buildsystem")
Signed-off-by: Zhang Jiao <zhangjiao2@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20250903063621.2424-1-zhangjiao2@cmss.chinamobile.com
[Bartosz: add Fixes tag, improve the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
diff --git a/tools/gpio/Makefile b/tools/gpio/Makefile
index ed565eb..342e056 100644
--- a/tools/gpio/Makefile
+++ b/tools/gpio/Makefile
@@ -77,7 +77,7 @@
 
 clean:
 	rm -f $(ALL_PROGRAMS)
-	rm -f $(OUTPUT)include/linux/gpio.h
+	rm -rf $(OUTPUT)include
 	find $(or $(OUTPUT),.) -name '*.o' -delete -o -name '\.*.d' -delete -o -name '\.*.cmd' -delete
 
 install: $(ALL_PROGRAMS)