PocketBook: Auto-standby plugin fix (#6612)
PocketBook: Auto-standby plugin fix (#6612)

Fix "accessing undefined variable" in previous commit.
koreader/koreader,Markismus/koreader,mwoz123/koreader,Hzj-jie/koreader,Frenzie/koreader,koreader/koreader,poire-z/koreader,pazos/koreader,poire-z/koreader,NiLuJe/koreader,Frenzie/koreader,NiLuJe/koreader