drm/i915/selftests: Align igt_spinner_create_request with hangcheck

Align igt_spinner_create_request with the hang_create_request
implementation in selftest_hangcheck.c.

Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230815165345.964068-2-jonathan.cavitt@intel.com