[][openwrt][mt7988][tops][fix coverity issue]

[Description]
Fix TOPS coverity issue

[Release-log]
N/A

Change-Id: Ic4a5aaf30e66e7985ef3d13e7448a626ee8ba124
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7922988
5 files changed