SdReadWrite can be called with a NULL Token for synchronous operations.
Add guard for DEBUG print to only print event pointer with Token is not
NULL.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>
5a16ba3ae1