Makefile: add trees to target all

Change-Id: If286b1a6abaeecb483a18ce62e720cb8d20eea4a
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/Makefile b/Makefile
index 666c9df..2d82418 100644
--- a/Makefile
+++ b/Makefile
@@ -36,7 +36,7 @@
 
 PYANG_OPTIONS := -Werror
 
-all: $(PYTHON_MODELS) pyangbind
+all: $(PYTHON_MODELS) pyangbind trees
 	$(MAKE) package
 
 trees: $(YANG_DESC_TREES) $(YANG_DESC_JSTREES) $(YANG_RECORD_TREES) $(YANG_RECORD_JSTREES)