[DOCS] cmake line incorrect for private stuff

If you look at;

https://doc.qt.io/qt-6/qtandroidprivate.html

you'll notice that the cmake instructions contain both a find_package and a target_link_libraries line.

For most actual libraries this is correct, but not for the private APIs as that isn't actually a separate library. For these documentation pages the suggested find_package line is confusing as using them will fail cmake with an error.

Notice that the target_link_libraries line is correct and should stay.