hw/intc: If mmsiaddrcfgh.L == 1, smsiaddrcfg and smsiaddrcfgh are read-only.

hw/intc: If mmsiaddrcfgh.L == 1, smsiaddrcfg and smsiaddrcfgh are read-only.

According to the `The RISC-V Advanced Interrupt Architecture`
document, if register `mmsiaddrcfgh` of the domain has bit L set
to one, then `smsiaddrcfg` and `smsiaddrcfgh` are locked as
read-only alongside `mmsiaddrcfg` and `mmsiaddrcfgh`.

Signed-off-by: Tommy Wu <tommy.wu@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Message-Id: <20230609055936.3925438-1-tommy.wu@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>