* add fp16 for layer_norm op

* revert layernorm api

* fix forward

* fix forward

* fix backward for layernorm with fp16

* fix unit test for layernorm with fp16

* fix with_mkldnn compile error for layernorm with fp16

* 1. revert to PADDLE_ENFORCE_NOT_NULL, 2. change static_cast<float> to static_cast<U>

* fix with_mkldnn compile error for layernorm with fp16

* fix with_mkldnn compile error for layernorm with fp16
Co-authored-by: Nzhiqiu <chenqiuliang@baidu.com>

* API/OP (group_norm, layer_norm, unpool) error message enhancement test=develop

restrict block num of layer_norm_grad cuda kernel to 128, test=develop

* add gelu plugin

* align trt bert with gpu

* add support for fused fc with relu,

* add unittest for bert trt