i965: Fix intel_miptree_is_fast_clear_capable()

i965: Fix intel_miptree_is_fast_clear_capable()

There are three types of fast clears:
  a. fast depth clears
  b. fast singlesample color clears
  c. fast multisample color clears
Function intel_miptree_is_fast_clear_capable() checks if a miptree
supports fast clears of type (b).

Rename the function to disambiguate what it does:
  old: intel_miptree_is_fast_clear_capable
  new: intel_miptree_supports_non_msrt_fast_clear

The functionally accidentally rejected multisampled color surfaces
because it thought they were singlesample array surfaces. Fix that by
explicitly rejecting surfaces with samples > 1.

This fix would have been needed before we enabled layered fast
singlesample color clears (introduced in gen8), which we want to do
eventually. For now, though, this patch changes no behavior; it just
fixes how the driver chooses its behavior.

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>