Revert "kconfig: qconf: Change title for the item window"

This reverts commit 5752ff07.

It added dead code to ConfigList:ConfigList().

The constructor of ConfigList has the initializer, mode(singleMode).

    if (mode == symbolMode)
           setHeaderLabels(QStringList() << "Item" << "Name" << "N" << "M" << "Y" << "Value");
    else
           setHeaderLabels(QStringList() << "Option" << "Name" << "N" << "M" << "Y" << "Value");

... always takes the else part.

The change to ConfigList::updateSelection() is strange too.
When you click the split view icon for the first time, the titles in
both windows show "Option". After you click something in the right
window, the title suddenly changes to "Item".

ConfigList::updateSelection() is not the right place to do this,
at least. It was not a good idea, I think.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>