Doc: Remove obsolete dependency to qtquickcontrols2

The documentation module for Qt Quick Controls 2 is now named simply
'qtquickcontrols'. Remove the obsolete dependency, and leave out the
dependency to the (now deprecated) Qt Quick Controls 1 docs.

Task-number: QTBUG-70333
Change-Id: Iac3ffbbf72c216c815f2434af991dfb6fa7f7b84
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>