propertydialog.py : Scrollable windows for long tooltips

In some cases, the length of the description and the brought
in by field was too big. That led to the size of the property
dialog exceeding Hob's size. For long tooltips we use
scrollable windows now.

[HOB #4321]

Signed-off-by: Andrei Dinu <andrei.adrianx.dinu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>