qapi/expr.py: Check for dict instead of OrderedDict

qapi/expr.py: Check for dict instead of OrderedDict

OrderedDict is a subtype of dict, so we can check for a more general
form. These functions do not themselves depend on it being any
particular type.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-Id: <20210421182032.3521476-4-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>