Commit 7779b1d7

, disabled clear support
when copying to/from color buffers. According to the performance CI, it
falls within a range of commits that introduced a performance regression
on Bioshock Infinite with Tigerlake. Icelake isn't noticeably affected.

By analyzing a trace of the game, I found a couple cases where that
commit added new partial resolves. Update get_copy_region_aux_settings
to avoid them:

- The trace uploads to R8_UNORM textures. On TGL, these enter the
  COMPRESSED_CLEAR state on the upload and are partially resolved before
  every subsequent upload. Thankfully, they keep their initial clear
  color of all zeroes. Since zeros can survive format reinterpretation,
  allow clear support for it.

- The trace copies between RGBA16_FLOAT textures. The ones with zero
  clear color are helped by the optimization above. The ones with
  non-zero clear color are used as source textures. Thankfully on ICL+,
  the clear color used for sampling is in pixel form and can thus be
  sampled from with format reinterpretation. Allow clear support for
  this case.

I haven't tested the actual performance impact of this change, but it
should be beneficial regardless.

Reported-by: Clayton Craft <clayton.a.craft@intel.com>
Reported-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <mesa/mesa!8262>