drm/xe: Convert page fault messages to be GT-oriented

drm/xe: Convert page fault messages to be GT-oriented

We are processing here G2H messages, so we should use GT oriented
messages to retain information about the origin GT.  While at it,
print error codes in a user-friendly way.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20250530164835.461-1-michal.wajdeczko@intel.com