drm/i915/guc: Add extra debug on CT deadlock

Print CT state (H2G + G2H head / tail pointers, credits) on CT
deadlock.

v2:
 (John Harrison)
  - Add units to debug messages

Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211214170500.28569-6-matthew.brost@intel.com