freedreno/regs: document SS6_UBO state src
Document this new a6xx_state_src value seen in A640/A650 tess traces.
(putting this in its own MR since not planning to use it in turnip)
Document this new a6xx_state_src value seen in A640/A650 tess traces.
(putting this in its own MR since not planning to use it in turnip)