Created by: grygielski

Suggested in https://github.com/PaddlePaddle/Paddle/pull/19510 changes to paddle::framework::vectorize() function. Following changes has allowed to get rid of vectorize2int() function from mkldnn ops.

@luotao1 Check if this modification is ok for You and let me know if I should swap vectorize2int() to vectorize<int>() in other files. They aren't maintained by us but since it's purely cosmetic change I think I can do it. This would require 2 more PR due to file limit.