target/riscv: Enable S*stateen bits for AIA

target/riscv: Enable S*stateen bits for AIA

As per the ratified AIA spec v1.0, three stateen bits control AIA CSR
access.

Bit 60 controls the indirect CSRs
Bit 59 controls the most AIA CSR state
Bit 58 controls the IMSIC state such as stopei and vstopei

Enable the corresponding bits in [m|h]stateen and enable corresponding
checks in the CSR accessor functions.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Message-ID: <20250110-counter_delegation-v5-3-e83d797ae294@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>