qapi: Improve error message for unexpected array types

qapi: Improve error message for unexpected array types

We reject array types in certain places with "cannot be an array".
Deleting this check improves the error message to "should be a type
name" or "should be an object or type name", depending on context, so
do that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230316071325.492471-6-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>