OPDS-PS: Fix hardcoded namespace in count (#9650)
OPDS-PS: Fix hardcoded namespace in count (#9650)

Turns out the namespace is dynamic, so, just look for ':count' and hope there won't be any conflicts ;).
poire-z/koreader,Frenzie/koreader,koreader/koreader,poire-z/koreader,NiLuJe/koreader,koreader/koreader,Frenzie/koreader,NiLuJe/koreader