do not look up the new outer band after shared memory promotion

The code looking up the new outer band was added in the prehistory
assuming that some steps following shared memory promotion in
makeWithOuterBlockInnerThreadStrategy may need it.  This is not and has
never been the case.  Given that shared memory promotion may now be
performed at an arbitrary depth, one can no longer assume any relation
between the shared memory promotion copies and the outer band.  Remove
the code looking up for the outer band.

Author: ftynse

tc/core/polyhedral/cuda/mapped_scop.cc

@@ -1088,13 +1088,6 @@ std::unique_ptr<MappedScop> MappedScop::makeWithOuterBlockInnerThreadStrategy(
           sharedMemorySize,
           cudaOptions.proto().unroll_copy_shared() &&
               generic.proto.has_unroll());
-
-      auto bands = ScheduleTree::collectDFSPreorder(
-          scop->scheduleRoot(), ScheduleTreeType::Band);
-      if (bands.size() == 0) { // Sanity check.
-        throw NoBandsException("no bands after promotion");
-      }
-      outerBand = bands[0];
     }
   }