fix: raise PMP faults for MMU-off accesses

[KnightGOKU]

Fixes #61

Summary

A PMP-denied load can hang when the MMU is bypassed because the access-fault logic waits for the delayed pmp_flg_vld signal. In this path, the fault may never be reported for the active load request.

Changes

• Include the current valid MMU-off request in the PMP fault qualification.
• Apply the same condition to both read and write permission checks:

pmp_flg_vld || dutlb_off_hit && lsu_mmu_va_vld_x

This allows a denied load to raise the expected access fault without waiting for the delayed PMP-valid signal.