drm/i915/mtl: X-Tile support changes to client blits

Refactor the supports_x_tiling and fast_blit_ok helper
functions in the live client selftest to better reflect
when XY_FAST_COPY_BLT supports X-tile and can be used.

Bspec: 47982
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230223183954.1817632-1-jonathan.cavitt@intel.com