[][openwrt][mt7988][pce][fix coverity defects]

[Description]
Fix PCE coverity defects

[Release-log]
N/A

Change-Id: I5137ce74b7358d74d58031dd9c8b82d446bbc5db
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8289365
3 files changed