target/riscv: Respect mseccfg.RLB bit for TOR mode PMP entry

target/riscv: Respect mseccfg.RLB bit for TOR mode PMP entry

When running in TOR mode (Top of Range) the next PMP entry controls
whether the entry is locked. However simply checking if the PMP_LOCK bit
is set is not sufficient with the Smepmp extension which now provides a
bit (mseccfg.RLB (Rule Lock Bypass)) to disregard the lock bits. In
order to respect this bit use the convenience pmp_is_locked() function
rather than directly checking PMP_LOCK since this function checks
mseccfg.RLB.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20250210153713.343626-1-rbradford@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>