drm/amd/amdgpu: cleanup coding style a bit

There is DEVICE_ATTR mechanism in separate attribute define.
So this change is to use attr array, also use
sysfs_create_files in init function & sysfs_remove_files in
fini function.
This maybe make the code a bit readable.
Signed-off-by: Bernard Zhao <bernard@vivo.com>

Changes since V1:
*Use DEVICE_ATTR mechanism

Link for V1:
*https://lore.kernel.org/patchwork/patch/1228076/

V2: make array const to fix build errors
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -148,6 +148,15 @@ static DEVICE_ATTR(mem_info_vis_vram_used, S_IRUGO,
 static DEVICE_ATTR(mem_info_vram_vendor, S_IRUGO,
 		   amdgpu_mem_info_vram_vendor, NULL);
 
+static const struct attribute *amdgpu_vram_mgr_attributes[] = {
+	&dev_attr_mem_info_vram_total.attr,
+	&dev_attr_mem_info_vis_vram_total.attr,
+	&dev_attr_mem_info_vram_used.attr,
+	&dev_attr_mem_info_vis_vram_used.attr,
+	&dev_attr_mem_info_vram_vendor.attr,
+	NULL
+};
+
 /**
  * amdgpu_vram_mgr_init - init VRAM manager and DRM MM
  *
@@ -172,31 +181,9 @@ static int amdgpu_vram_mgr_init(struct ttm_mem_type_manager *man,
 	man->priv = mgr;
 
 	/* Add the two VRAM-related sysfs files */
-	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_total);
-	if (ret) {
-		DRM_ERROR("Failed to create device file mem_info_vram_total\n");
-		return ret;
-	}
-	ret = device_create_file(adev->dev, &dev_attr_mem_info_vis_vram_total);
-	if (ret) {
-		DRM_ERROR("Failed to create device file mem_info_vis_vram_total\n");
-		return ret;
-	}
-	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_used);
-	if (ret) {
-		DRM_ERROR("Failed to create device file mem_info_vram_used\n");
-		return ret;
-	}
-	ret = device_create_file(adev->dev, &dev_attr_mem_info_vis_vram_used);
-	if (ret) {
-		DRM_ERROR("Failed to create device file mem_info_vis_vram_used\n");
-		return ret;
-	}
-	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_vendor);
-	if (ret) {
-		DRM_ERROR("Failed to create device file mem_info_vram_vendor\n");
-		return ret;
-	}
+	ret = sysfs_create_files(&adev->dev->kobj, amdgpu_vram_mgr_attributes);
+	if (ret)
+		DRM_ERROR("Failed to register sysfs\n");
 
 	return 0;
 }
@@ -219,11 +206,7 @@ static int amdgpu_vram_mgr_fini(struct ttm_mem_type_manager *man)
 	spin_unlock(&mgr->lock);
 	kfree(mgr);
 	man->priv = NULL;
-	device_remove_file(adev->dev, &dev_attr_mem_info_vram_total);
-	device_remove_file(adev->dev, &dev_attr_mem_info_vis_vram_total);
-	device_remove_file(adev->dev, &dev_attr_mem_info_vram_used);
-	device_remove_file(adev->dev, &dev_attr_mem_info_vis_vram_used);
-	device_remove_file(adev->dev, &dev_attr_mem_info_vram_vendor);
+	sysfs_remove_files(&adev->dev->kobj, amdgpu_vram_mgr_attributes);
 	return 0;
 }