WelcomePage: reducing size of view

Otherwise we might get an unnecessary scrollbar.

Change-Id: I12ab2288a02f32f542420b0e979c24aeaa00522d
Reviewed-on: http://codereview.qt-project.org/6063


Reviewed-by: Daniel Teske <daniel.teske@nokia.com>
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@nokia.com>