[RFC] dt-bindings: riscv: enum for riscv,isa

[Heinrich Schuchardt <xypron.glpk@xxxxxx>]

In Documentation/devicetree/bindings/riscv/cpus.yaml I find for riscv,isa:

    enum:
      - rv64imac
      - rv64imafdc

This implies that 'rv64imafc' or 'rv64imafdqc' would be illegal values
while these combinations of extensions would be compliant with "The
RISC-V Instruction Set Manual".

To me it does not make much sense to try to enumerate all permissible
permutations of RISC-V extensions.

Shouldn't this enum be removed and replaced by examples?

Best regards

Heinrich