* Replace mutable_data with DeviceContext.Alloc in phi kernels

* Fix CI errors

* Fix CI errors

* Fix CI errors, test=kunlun

* Fix CI errors, test=kunlun

* Handle rnn_functor

* Update approvals

* perfect copy

* deal with conflict

* deal with conflict

* fix compile bugs

* fix unittest bugs

* change code format

* deal with conflict

* modify code by review

* fix ce bugs

* fix ce bugs

* add lo

* perfect code format

* deal with conflicts

* move elementwise_div grad

* change mutable_data to alloc

* fix compile bugs

* move reduce gpu impl funcs into pten/kernels/funcs

* change reduce header name and namespace

* fix spell word error

* change mutable_data to dev_ctx.Alloc

* modify place to devcontex

* format code style

* fix build error

* fix build error

* fix conflict

* move elementwise function to funcs directory

* fix compile bugs

* modify according to comment