drm/xe: Simplify module initialization code

drm/xe: Simplify module initialization code

There is no need to have extra checks and WARN() in the helpers
as instead of an index of the entry with function pointers, we
can pass pointer to the entry which we prepare directly in the
main loop, that is guaranteed to be valid.

  add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-180 (-180)
  Function                                     old     new   delta
  xe_exit                                      109      79     -30
  cleanup_module                               109      79     -30
  xe_init                                      248     188     -60
  init_module                                  248     188     -60
  Total: Before=2774145, After=2773965, chg -0.01%

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250731193339.179829-2-michal.wajdeczko@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>