drm/xe/guc: Fix arguments passed to relay G2H handlers

By default CT code was passing just payload of the G2H event
message, while Relay code expects full G2H message including
HXG header which contains DATA0 field. Fix that.

Fixes: 26d4481a ("drm/xe/guc: Start handling GuC Relay event messages")
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240419150351.358-1-michal.wajdeczko@intel.com