Add the bindings for the Bifrost family of ARM Mali GPUs.

The Bifrost GPU architecture is similar to the Midgard family,
but with a different Shader Core & Execution Engine structures.

Bindings are based on the Midgard family bindings, but the inner
architectural changes makes it a separate family needing separate
bindings.

The Bifrost GPUs are present in a number of recent SoCs, like the
Amlogic G12A Family, and many other vendors.
The Amlogic vendor specific compatible is added to handle the
specific IP integration differences and dependencies.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
[narmstrong: fixed small typo in compatible description]
Link: https://patchwork.freedesktop.org/patch/msgid/20190401080949.14550-1-narmstrong@baylibre.com