target/riscv: add riscv_cpu_accelerator_compatible()

target/riscv: add riscv_cpu_accelerator_compatible()

Add an API to check if a given CPU is compatible with the current
accelerator.

This will allow query-cpu-model-expansion to work properly in conditions
where QEMU supports both accelerators (TCG and KVM), QEMU is then
launched using TCG, and the API requests information about a KVM only
CPU (e.g. 'host' CPU).

KVM doesn't have such restrictions and, at least in theory, all CPUs
models should work with KVM. We will revisit this API in case we decide
to restrict the amount of KVM CPUs we support.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231018195638.211151-6-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>