pylibfdt: Use Makefile constructs to implement NO_PYTHON

The current mechanism uses a shell construct, but it seems better to use
a Makefile approach.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

pylibfdt/Makefile.pylibfdt

@@ -25,11 +25,4 @@ install_pylibfdt: $(WRAP) $(PYMODULE)
 	$(call run_setup, $(PYLIBFDT_srcs) $(WRAP), \
 		install $(if $(SETUP_PREFIX),--prefix=$(SETUP_PREFIX)))
 
-maybe_install_pylibfdt:
-	if [ -e $(PYMODULE) ]; then \
-		if [ -z "$(NO_PYTHON)" ]; then \
-			$(MAKE) install_pylibfdt; \
-		fi; \
-	fi
-
 PYLIBFDT_cleanfiles = libfdt_wrap.c libfdt.py libfdt.pyc _libfdt.so