tools: ynl: remove __pycache__ during clean

Build process uses python to generate the user space code.
Remove __pycache__ on make clean.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/net/ynl/lib/Makefile

@@ -17,6 +17,7 @@ ynl.a: $(OBJS)
 	ar rcs $@ $(OBJS)
 clean:
 	rm -f *.o *.d *~
+	rm -rf __pycache__
 
 distclean: clean
 	rm -f *.a