gallium/u_threaded_context: remove stale comment
We're now using PIPE_SHADER_MAX_SAMPLER_VIEWS, so this advice is outdated.
Fixes: 620c5e9d ("gallium/u_threaded_context: Use PIPE_MAX_SHADER_SAMPLER_VIEWS for sampler_buffers")
We're now using PIPE_SHADER_MAX_SAMPLER_VIEWS, so this advice is outdated.
Fixes: 620c5e9d ("gallium/u_threaded_context: Use PIPE_MAX_SHADER_SAMPLER_VIEWS for sampler_buffers")