TensorVolumePatchOp: Suppress Wmaybe-uninitialized caused by unreachable code

unsupported/Eigen/CXX11/src/Tensor/TensorVolumePatch.h

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorVolumePatch.h b/unsupported/Eigen/CXX11/src/Tensor/TensorVolumePatch.h
index d8faa4d..2f0c135 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorVolumePatch.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorVolumePatch.h
@@ -274,8 +274,10 @@
           m_colPaddingLeft = dx / 2;
           break;
         }
-        default:
+        default: {
           eigen_assert(false && "unexpected padding");
+          return;
+        }
       }
     }
     eigen_assert(m_outputRows > 0);