[PATCH] Remove broken prefetching in free_one_pgd()

This looks extremely suspect to me, and seems like
it will prefetch past the end of the pmd, which is a no no.

mm/memory.c

@@ -113,10 +113,8 @@ static inline void free_one_pgd(mmu_gather_t *tlb, pgd_t * dir)
 	}
 	pmd = pmd_offset(dir, 0);
 	pgd_clear(dir);
-	for (j = 0; j < PTRS_PER_PMD ; j++) {
-		prefetchw(pmd+j+(PREFETCH_STRIDE/16));
+	for (j = 0; j < PTRS_PER_PMD ; j++)
 		free_one_pmd(tlb, pmd+j);
-	}
 	pmd_free_tlb(tlb, pmd);
 }