target/riscv: add RVA23U64 profile

target/riscv: add RVA23U64 profile

Add RVA23U64 as described in [1]. Add it as a child of RVA22U64 since
all RVA22U64 mandatory extensions are also present in RVA23U64. What's
left then is to list the mandatory extensions that are RVA23 only.

A new "rva23u64" CPU is also added.

[1] https://github.com/riscv/riscv-profiles/blob/main/src/rva23-profile.adoc

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250115184316.2344583-6-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>