Fix mmu_invalidate_range for 8×2 set-associative

[jserv]

The function was attempting to access n_pages directly on mmu_cache_set_t structures, which don't have this member. The correct access path is cache_load[set].ways[way].n_pages for the 8-set × 2-way architecture.

The fix ensures all 16 load cache entries and 16 store cache entries are properly checked during range invalidation operations (e.g., SFENCE.VMA).

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Summary by cubic

Fixed mmu_invalidate_range to correctly handle 8×2 set-associative load/store caches by iterating over sets and ways. Ensures SFENCE.VMA and range invalidations clear all relevant entries and prevent stale translations.

• Bug Fixes
  • Use cache_*[set].ways[way].n_pages instead of accessing n_pages on mmu_cache_set_t.
  • Invalidate all 16 load and 16 store entries; fetch cache handled separately.

^{Written for commit ebe49d9. Summary will update automatically on new commits.}