drm/xe/uc: Reorder post hwconfig uC initialization step

We want to move the GuC submission initialization to the post
hwconfig step, but now this step is done too late as migration
initialization uses exec_queue that would crash due to a unset
exec_queue_ops. We can easily fix that by small function reorder.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240510203810.1952-2-michal.wajdeczko@intel.com