drm/xe: Introduce GT oriented log messages

While debugging GT related problems, it's good to know which GT was
reporting problems. Introduce helper macros to allow prefix GT logs
with GT identifier. We will use them in upcoming patches.

v2: use xe_ prefix (Lucas)
v3: use correct include

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>