[pvr] fix unexpected jumping of selected item if notified by observable

In some cases we refresh the entire item list if we get a notification from the observable. This updates m_selectedItemPaths in Notify() to prevent the selected item from jumping.
Merge pull request #5372 from xhaggi/pvr-fix-selecteditem-jumps-after-notify

[pvr] fix unexpected jumping of selected item if notified by observable