drm/xe/uc: Use GT-oriented firmware messages

drm/xe/uc: Use GT-oriented firmware messages

We are already prepared to define firmwares per-GT type, so we
should also prepare our messages to be GT-oriented.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250606204311.813-1-michal.wajdeczko@intel.com