pytools: obmcutil: Use format string for all-props output

Change-Id: I9d803da8c0ff8862039bb5b7adc07952208820d1
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/pytools/obmcutil b/pytools/obmcutil
index 9bb8428..d0db8b5 100644
--- a/pytools/obmcutil
+++ b/pytools/obmcutil
@@ -83,7 +83,7 @@
         dbus_iface = dbus.Interface(dbus_obj, "org.freedesktop.DBus.Properties")
         props = dbus_iface.GetAll(iface)
         for p in props:
-            print p + " = " + str(props[p])
+            print "{} = {}".format(p, str(props[p]))
 
 def run_all_commands(dbus_bus, recipe):
     if isinstance(recipe, dict):