Fix wrong attribute name for geometry_thin_walled#292

AdrienHerubel merged 2 commits intoAcademySoftwareFoundation:dev_1.2AcademySoftwareFoundation/OpenPBR:dev_1.2from

msuzuki-nvidia:fix-geometry-thin-walledmsuzuki-nvidia/OpenPBR:fix-geometry-thin-walledCopy head branch name to clipboard