drm/xe: Define helper for GT specific debugfs files

Many of our debugfs files are GT specific and require a pointer to
struct xe_gt to correctly show its content.  Our initial approach
to use drm_info_list.data field to pass pointer not only requires
extra steps (like copying template per each GT) but also abuses
the rule that this data field should not be device specific.

Introduce helper function that will use xe_gt pointer stored at
parent directory level and use .data only to pass actual print
function that would expects xe_gt pointer as a parameter.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://lore.kernel.org/r/20240214115756.1525-3-michal.wajdeczko@intel.com


Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240328162808.451-3-michal.wajdeczko@intel.com