perf(baidu_netdisk): reduce the number of file listing requests (OpenListTeam#2016)

* 本优化减少了百度网盘驱动下文件列表的请求次数，能加快文件浏览速度。此前只要文件夹下有至少一个文件，都会至少发出2次列表请求。

Signed-off-by: hcrgm <hcrgm@qq.com>

Author: hcrgm

drivers/baidu_netdisk/util.go

@@ -152,7 +152,7 @@ func (d *BaiduNetdisk) postForm(pathname string, params map[string]string, form
 
 func (d *BaiduNetdisk) getFiles(dir string) ([]File, error) {
 	start := 0
-	limit := 200
+	limit := 1000
 	params := map[string]string{
 		"method": "list",
 		"dir":    dir,
@@ -168,7 +168,6 @@ func (d *BaiduNetdisk) getFiles(dir string) ([]File, error) {
 	for {
 		params["start"] = strconv.Itoa(start)
 		params["limit"] = strconv.Itoa(limit)
-		start += limit
 		var resp ListResp
 		_, err := d.get("/xpan/file", params, &resp)
 		if err != nil {
@@ -187,6 +186,11 @@ func (d *BaiduNetdisk) getFiles(dir string) ([]File, error) {
 		} else {
 			res = append(res, resp.List...)
 		}
+
+		if len(resp.List) < limit {
+			break
+		}
+		start += limit
 	}
 	return res, nil
 }