[mlir][bufferization] Remove unused function

Author: maerhart

mlir/lib/Dialect/Arith/Transforms/BufferDeallocationOpInterfaceImpl.cpp

@@ -16,8 +16,6 @@
 using namespace mlir;
 using namespace mlir::bufferization;
 
-static bool isMemref(Value v) { return v.getType().isa<BaseMemRefType>(); }
-
 namespace {
 /// Provides custom logic to materialize ownership indicator values for the
 /// result value of 'arith.select'. Instead of cloning or runtime alias