drm/amdgpu: remove dead code after hmm_range_fault()

Since amdgpu does not use the snapshot mode of hmm_range_fault() a
successful return already proves that all entries in the pfns are
HMM_PFN_VALID, there is no need to check the return result of
hmm_device_entry_to_page().

Link: https://lore.kernel.org/r/3-v2-b4e84f444c7d+24f57-hmm_no_flags_jgg@mellanox.comAcked-by: NFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -862,17 +862,13 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 		goto out_free_pfns;
 	}
 
-	for (i = 0; i < ttm->num_pages; i++) {
-		/* FIXME: The pages cannot be touched outside the notifier_lock */
+	/*
+	 * Due to default_flags, all pages are HMM_PFN_VALID or
+	 * hmm_range_fault() fails. FIXME: The pages cannot be touched outside
+	 * the notifier_lock, and mmu_interval_read_retry() must be done first.
+	 */
+	for (i = 0; i < ttm->num_pages; i++)
 		pages[i] = hmm_device_entry_to_page(range, range->pfns[i]);
-		if (unlikely(!pages[i])) {
-			pr_err("Page fault failed for pfn[%lu] = 0x%llx\n",
-			       i, range->pfns[i]);
-			r = -ENOMEM;
-
-			goto out_free_pfns;
-		}
-	}
 
 	gtt->range = range;
 	mmput(mm);