[][openwrt][common][app][Fix switch issues detected by Coverity]

[Description]
Fix issues detected by Coverity scan,
CID 5237903,5237902,5237900,5237898

[Release-log]
N/A


Change-Id: I904d253baf3f8235f94873d8514c02cc3b6f655f
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8855775
1 file changed