* cleanup unused code

* unify is_int8 is_bfloat16

* Simplify matmul_v2 FWD kernel

* remove RunKernel methods

* remove import namespace

* remove headers

* clean fluid/phi cross imports

* remove fluid axpy_handler

* delete fluid methods

* activations

* OneDNNMemDesc

* MKLDNNFormatForSize

* MatchShapeToLayout

* MKLDNNMemoryFormat

* MKLDNNFormat

* ReorderMKLDNNHandler

* to_void_cast

* review suggestions

* interpolate

* remove fluid depedency

* namespace modify

* update by comment

* delete_quantize_headerfile

* delete_requantize_headerfile

* Add operator checkpoints for new attributes.

* Fix adding subsequent checkpoint to quantize op.

* Add checkpoint to quantize

* Change bfloat16 option

* Enable quantize to reorder to nchw as well

* Correct FC MKL-DNN input dim requirements to accept 3D

* Improve DNNL FC format, error and 3D input handling

test=develop

* Improve error checking in FC

test=develop

* Improve PADDLE_ENFORCE messages in fc-related files

* Remove data layout attribute from obligatory pass args

test=develop

* Fix message in fc_mkldnn_pass to be logically correct

test=develop

* replace part of the old implementation, test=develop

* restore concat op, test=develop

* update all ops implemention & delete GetDataTypeOfVar func, test=develop

* add pybind interface to get all inplace ops, test=develop

* enhance OpTest to check whether the consistency of operator when using and not using inplace, test=develop

* handle corner cases in op_test, test=develop

* support outputs without tensor holder_, like XShape in reshape_op, test=develop

* fix bug, some op has GradOpMaker, but actually no grad_op in OpInfoMap, test=develop

* use reshape_grad instead of reshape in FlattenGradOp, test=develop

* fix error debug dims info for variables like XShape, test=develop

* change computational order in sum_op to relieve computation difference using inplace, test=develop

* add inplace_atol to check group_norm, and skip inplace_grad for mkldnn, test=develop

* follow sneaxiy's comments, test=develop

* remove unused DefaultGradOpDescMaker in mkldnn op, test=develop

test=develop