freedreno, turnip: Disable 8bpp UBWC on a650
While it doesn't immediately hang like on a660, it seems to be buggy and the blob disables it.
This fixes a bunch of r8_* dEQP-VK tests, which seem to pass individually but don't work when run after other tests. For example this fixes failures running dEQP-VK.pipeline.sampler..r8_uint.