drm/xe/device: fix XE_MAX_GT_PER_TILE check

drm/xe/device: fix XE_MAX_GT_PER_TILE check

Here XE_MAX_GT_PER_TILE is the total, therefore the gt index should
always be less than.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240318180532.57522-5-matthew.auld@intel.com
(cherry picked from commit a5ef563b1d676548a4c5016540833ff970230964)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>