This adds all the relevant bits and pieces to add a `shgemv` path as
well as a future `hgemm`/`hgemv` path in a similar model to `sb` and `b`
interfaces.
I've also fixed a few bits and pieces around `shgemm` which didn't build
in a few situations.
- Sets up all the various entrypoints for `bgemv`
- Adds `bscal` for use in the `bgemv` interface
- Adds test cases for comparing `sgemv` and `bgemv`
- Adds generic kernels for `bgemv_n` and `bgemv_t` which are accurate
enough to pass above tests
1. Add a new API -- sbgemv to support bfloat16 based gemv
2. Implement a generic kernel for sbgemv
3. Implement an avx512-bf16 based kernel for sbgemv
Signed-off-by: Chen, Guobing <guobing.chen@intel.com>
