Fix initialization value of SpinBox

The maximumValue 99 was enforced on value _before_ we had a chance
to update it. This made it sometimes impossible to get a maximumValue
higher than 99.

Change-Id: Ia07a9271d563fd3496b583757df757c1e7b4ceb5
Reviewed-by: Caroline Chao <caroline.chao@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>