[AVL6211] DVB-API v5 Support

Fix AVL6211_Read_Signal_Strength / AVL6211_Read_Snr
[0% - 100%] => [0 - 65535]
Fix AVL6211_Set_Frontend
Fix frontend capabilities / frontent calls

from:
https://github.com/J1nx-Hackable-Gadgets/buildroot-linux-kernel-m3/commit/f1749362873a15a546a447ff6339a899446c8abf