[SAC] Use NULL for null pointer in last argument in HeadlessDispatch() calls.

drivers/sac/driver/conmgr.c

···
                                   &EnablePaging,
                                   sizeof(EnablePaging),
                                   NULL,
-                                  0);
+                                  NULL);
         if (!NT_SUCCESS(Status)) SAC_DBG(SAC_DBG_INIT, "SAC Display Log failed.\n");
     }
     else if (!strncmp(InputBuffer, "cmd", 3))

drivers/sac/driver/data.c

···
                               &EnableData,
                               sizeof(EnableData),
                               NULL,
-                              0);
+                              NULL);
     if (!NT_SUCCESS(Status))
     {
         /* Bail out if we couldn't even get this far */
···
                                   &EnableData,
                                   sizeof(EnableData),
                                   NULL,
-                                  0);
+                                  NULL);
         if (!NT_SUCCESS(Status)) SAC_DBG(SAC_DBG_INIT, "Failed dispatch\n");
 
         /* Bail out */