dt-bindings: gpu: mali-valhall-csf: Add support for Arm Mali CSF GPUs

Arm has introduced a new v10 GPU architecture that replaces the Job Manager
interface with a new Command Stream Frontend. It adds firmware driven
command stream queues that can be used by kernel and user space to submit
jobs to the GPU.

Add the initial schema for the device tree that is based on support for
RK3588 SoC. The minimum number of clocks is one for the IP, but on Rockchip
platforms they will tend to expose the semi-independent clocks for better
power management.

v4:
- Fix formatting issue

v3:
- Cleanup commit message to remove redundant text
- Added opp-table property and re-ordered entries
- Clarified power-domains and power-domain-names requirements for RK3588.
- Cleaned up example

Note: power-domains and power-domain-names requirements for other platforms
are still work in progress, hence the bindings are left incomplete here.

v2:
- New commit

Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>