[gui] adds new method GetSelectedItemPath() to CGUIViewControl
[pvr] fix: remember the wrong selected item path if you close the channel osd

If you close the channel osd on a different group than the current playing group without switching to a channel of this group, the wrong selected item path is stored in the global variable. This fix it by setting the proper selected item of the current playing group.
[pvr] use new GetSelectedItemPath() method in CGUIWindowPVRBase
Merge pull request #5447 from xhaggi/pvr-fix-wrong-selected-item

[pvr] fix: remember the wrong selected item path if you close the channel osd