Explicit instantiation of lrn test driver with bfloat16 type (#2073)
Explicit instantiation of lrn test driver with bfloat16 type (#2073)

* Explicit instantiation of lrn test driver with bfloat16 type so as to avoid compiler issues reported in SWDEV-202752.
* Resolve static check and use pow from std library
* Resolve compile error in half data type path as std::pow doesn't have support for half and half datatype doesn't seem to have defined conversion to float on pow. So, pow from hip needs to be invoked
* Invoke std::pow with explicit conversion as rocblas library seems to have remove pow function with half or bfloat16 type
* Invoke std::pow with explicit conversion as rocblas library seems to have remove pow function with half or bfloat16 type
* Further reduce chance of compilation error by explicit cast operation

ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen