sdbus++: property: invalid Python symbol

The `is_enum` function tried to use `false` when it meant `False`.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6fb52ee49acad48861ef7c83246d93973eab1bc0
diff --git a/tools/sdbusplus/property.py b/tools/sdbusplus/property.py
index a3f43eb..23c0ba7 100644
--- a/tools/sdbusplus/property.py
+++ b/tools/sdbusplus/property.py
@@ -52,7 +52,7 @@
 
     def is_enum(self):
         if not self.typeName:
-            return false
+            return False
         return 'enum' == self.__type_tuple()[0]
 
     def is_integer(self):