viewport: Don't needlessly set adjustment value
viewport: Don't needlessly set adjustment value

Don't set the adjustment value during allocation, MxAdjustment already
clamps the value when changing the other properties on adjustment and
doing so may accidentally stop any interpolation animation that may be
running.

Fixes MeeGo bug #1385

jonnylamb/mx,clutter-project/mx,jonnylamb/mx,clutter-project/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx,pwithnall/mx,pwithnall/mx,pwithnall/mx