Deprecate n_support_  and class_weight_ from SVR class

the SVR class has attributes n_support_  and class_weight_ which should be deprecated

per https://github.com/scikit-learn/scikit-learn/pull/14773#discussion_r317371146 There is no n_class, therefore there should not be n_support_ or class_weight_ attributes