drm/xe: Add GuC state asserts to deregister_exec_queue

Will help catch bugs in GuC state machine.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240611144053.2805091-9-matthew.brost@intel.com