drm/xe: Drop skip_mtcfg descriptor flag

drm/xe: Drop skip_mtcfg descriptor flag

The skip_mtcfg descriptor flag is unused and expected to remain that
way.  Drop it.

Single-tile platforms are already identified by a zero/unset value for
max_remote_tiles and don't need/use this flag to avoid trying to read
out multi-tile configuration.  PVC is currently the only multi-tile
platform, and PVC uses MTCFG so this flag is not set.  The current
expectation is that if/when future multi-tile platforms show up, they
will also use the MTCFG register in the same manner as PVC, meaning that
they won't have any need to set 'skip_mtcfg' either.

Even if a future platform does change how multi-tile configuration gets
probed (e.g., using some different register), simply doing an early return
from xe_info_probe_tile_count() would probably not be the correct logic
to handle that anyway.

Bspec: 53146
Reviewed-by: Xin Wang <x.wang@intel.com>
Link: https://patch.msgid.link/20260416-no-skip-mtcfg-v1-1-c8ea26d81530@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>