Add support for PocketBook InkPad X (#5890)
Add support for PocketBook InkPad X (#5890)

Closes #5887.
mwoz123/koreader,Hzj-jie/koreader,Markismus/koreader,Frenzie/koreader,pazos/koreader,NiLuJe/koreader,mihailim/koreader,koreader/koreader,poire-z/koreader,poire-z/koreader,Frenzie/koreader,koreader/koreader,NiLuJe/koreader