i965: Correct a mistake that always forced texture tiling.

i965: Correct a mistake that always forced texture tiling.

Regression since commit 3a31876600, when tiling modes were moved into
layout_flags.

The relevant enum values are

   MIPTREE_LAYOUT_ALLOC_YTILED = 1 << 5
   MIPTREE_LAYOUT_ALLOC_XTILED = 1 << 6
   MIPTREE_LAYOUT_ALLOC_ANY_TILED = MIPTREE_LAYOUT_ALLOC_YTILED |
                                    MIPTREE_LAYOUT_ALLOC_XTILED
   MIPTREE_LAYOUT_ALLOC_LINEAR = 1 << 7

so the expression (layout_flags & MIPTREE_LAYOUT_ALLOC_ANY_TILED) can
never produce a value of MIPTREE_LAYOUT_ALLOC_LINEAR.

The enum this replaced was

   enum intel_miptree_tiling_mode {
      INTEL_MIPTREE_TILING_ANY,
      INTEL_MIPTREE_TILING_Y,
      INTEL_MIPTREE_TILING_NONE,
   };

where "ANY" means "Y" or "NONE" (i.e., linear). As such, remove the
unused (and worse, unhandled) MIPTREE_LAYOUT_ALLOC_XTILED and redefine
MIPTREE_LAYOUT_ALLOC_ANY_TILED to mean what it did before.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91513
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>