[][openwrt][app][Fix Coverity defects in the switch utility, Part3]

[Description]
Fix miscellaneous coverity defects

[Release-log]
N/A


Change-Id: I8196182950e3f0be51a6cd79ca5baf0b614972dd
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/9230902
1 file changed