* add reduce_sum grad kernel

* add reduce_grad

* modify reduce grad

* update reduce grad functions

* fix build error

* add argument mapping

* move cast input after grad

* add dims.size=1 cpu reduce_sum grad compute method

* update reduce grad GPU

* remove raw reduce_sum_grad kernel

* modify header files

* add namespace funcs for reduce_grad_funcstions

* rename pten dir to phi

* rename namespace to phi

* rename infrt pten dir to phi

* resolve conflict

* rename pten to phi in cmake

* revert all infrt change

* change needed files

* fix infrt failed

* fix inference failed