dt-bindings: gpu: mali-bifrost: Add Allwinner H616 compatible

The Allwinner H616 SoC has a Mali-G31 MP2 GPU, which is of the Mali
Bifrost family.
Add the SoC specific compatible string and pair it with the bifrost
fallback compatible.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20250221005802.11001-4-andre.przywara@arm.com


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>