Created by: wozna

This PR adds BF16 to framework.proto file.
It is related to https://github.com/PaddlePaddle/Paddle/pull/25402 PR that also adds BF16 to framework.proto to Paddle.

In Paddles PR there was a problem in building Paddle with Paddle-Lite. It seems that the Paddle-Lite proto files have priority over the Paddle ones what cause that BF16 is not visible.

This is a tested workaround that resolves that problem that was mentioned in this comment: https://github.com/PaddlePaddle/Paddle/pull/25402#issuecomment-684514106