* [NNVM][TENSORFLOW] Optimized tensorflow testcases

* Replace Constants with Placeholder

* Review comment fix

* Use int for int8x4 due to performance overhead of char4

* Add a comment about using int

* Remove invalid test

* [TOPI] add injective scheduler for HLS backends

* Introduced PrintBinaryExpr

* Separate fusion and compilation

* fix description of graph_fuse.h

* fix lint

* fix @masahi 's comments, move fusion out of target

* fix graph passing and make fused_entries singula in graph attr

* fix typo

* fix some comments

* run test again

* remove rvalue for graphfuse and graphfindfusiablegroups

* LRN support for ONNX

* [ONNX] Updated lrn testcases

* [FRONTEND][TENSORFLOW] Add Pad and PadV2 support

* Add assettion to _pad, and fix testcase for pad.