drm/i915: Update tiled blits selftest

Update the selftest to include Tile 4 mode and switch to Tile 4 on
platforms that supports Tile 4 but no Tile Y and vice versa.
Also switch to XY_FAST_COPY_BLT on platforms that supports it.

v4: update commit message to reflect the code changes properly.
v3: add a function to find X-tile availability for a platform.
v2: disable Tile X for iGPU in fastblit and
    fix checkpath --strict warnings.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5879


Signed-off-by: Bommu Krishnaiah <krishnaiah.bommu@intel.com>
Co-developed-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220516082015.32020-1-nirmoy.das@intel.com