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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[Bartosz: add Fixes tag, improve the commit message]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

tools/gpio/Makefile

···
 
 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)