drm/i915/guc: Update guc_err message to show outstanding g2h responses

Updating the guc_error message to show how many g2h responses
are still outstanding, in order to help with future debugging.

Signed-off-by: Jesus Narvaez <jesus.narvaez@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241213204720.3918056-1-jesus.narvaez@intel.com