[pvr] apply the view state handling on a per window basis

As reported in our forum at http://forum.xbmc.org/showthread.php?tid=175135&pid=1776697#pid1776697 the view state handling depends on the current selected group. This changes the handling to be on a per window basic instead.
Merge pull request #5255 from xhaggi/pvr-apply-view-state-on-a-per-window-basis