drm/i915/guc: Update GuC messages in intel_guc_ct.c

Use new macros to have common prefix that also include GT#.

v2: drop unused helpers

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230128195907.1837-5-michal.wajdeczko@intel.com