This new abstract type will be used to differentiate between static and
non-static CPUs in query-cpu-definitions.

All generic CPUs were changed to be of this type. Named CPUs are kept as
TYPE_RISCV_CPU and will still be considered static.

This is the output of query-cpu-definitions after this change for the
riscv64 target:

$ ./build/qemu-system-riscv64 -S -M virt -display none -qmp stdio
{"QMP": {"version": (...)}
{"execute": "qmp_capabilities", "arguments": {"enable": ["oob"]}}
{"return": {}}
{"execute": "query-cpu-definitions"}
{"return": [
{"name": "rv64", "typename": "rv64-riscv-cpu", "static": false, "deprecated": false},
{"name": "sifive-e51", "typename": "sifive-e51-riscv-cpu", "static": true, "deprecated": false},
{"name": "any", "typename": "any-riscv-cpu", "static": false, "deprecated": false},
{"name": "x-rv128", "typename": "x-rv128-riscv-cpu", "static": false, "deprecated": false},
{"name": "shakti-c", "typename": "shakti-c-riscv-cpu", "static": true, "deprecated": false},
{"name": "thead-c906", "typename": "thead-c906-riscv-cpu", "static": true, "deprecated": false},
{"name": "sifive-u54", "typename": "sifive-u54-riscv-cpu", "static": true, "deprecated": false}
]}

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230411183511.189632-4-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>