Add accessors to read class error code from NV_PGRAPH_CLASS_ERROR Bug 200010403 Change-Id: Ia99f50e264f9b8aa93f99994e52424418a2e4f74 Signed-off-by: Deepak Nibade <dnibade@nvidia.com> Reviewed-on: http://git-master/r/419565 Reviewed-by: Automatic_Commit_Validation_User GVS: Gerrit_Virtual_Submit Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>