Camera2: Doc entries no longer have type='enum', instead they use enum='true'

* This allows all entries to have any backing type
        (usually a byte, but for availableFormats it's int32)
* No longer need special casing for availableFormats
* No longer need to coerce an enum type into a byte

Change-Id: Ib1d4b93521e90f243b54f66c3d4c4b35032bc06a
diff --git a/camera/docs/metadata_parser_xml.py b/camera/docs/metadata_parser_xml.py
index cadbac1..d42a8b4 100755
--- a/camera/docs/metadata_parser_xml.py
+++ b/camera/docs/metadata_parser_xml.py
@@ -146,7 +146,7 @@
     #
     # Enum
     #
-    if entry['type'] == 'enum':
+    if entry.get('enum', 'false') == 'true':
 
       enum_values = []
       enum_optionals = []
@@ -171,6 +171,7 @@
       d['enum_optionals'] = enum_optionals
       d['enum_notes'] = enum_notes
       d['enum_ids'] = enum_ids
+      d['enum'] = True
 
     #
     # Container (Array/Tuple)