drm/xe: Refactor GT debugfs

drm/xe: Refactor GT debugfs

We are abusing struct drm_info_list.data by storing there pointer
to the xe_gt, while it shouldn't be used for any device specific
data.  Use recently introduced xe_gt_debugfs_simple_show() that
hides all details how to obtain the xe_gt pointer.  This will also
remove the need for making copies of the struct drm_info_list
to get GT specific definitions.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://lore.kernel.org/r/20240214115756.1525-4-michal.wajdeczko@intel.com
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240328162808.451-4-michal.wajdeczko@intel.com