target/riscv: Add counter delegation/configuration support

target/riscv: Add counter delegation/configuration support

The Smcdeleg/Ssccfg adds the support for counter delegation via
S*indcsr and Ssccfg.

It also adds a new shadow CSR scountinhibit and menvcfg enable bit (CDE)
to enable this extension and scountovf virtualization.

Signed-off-by: Kaiwen Xue <kaiwenx@rivosinc.com>
Co-developed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Message-ID: <20250110-counter_delegation-v5-8-e83d797ae294@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>