Add the correct vertical positioning for clock

Calculate the top padding of the large clock in the context of being in
a column. The old calculation is the relative positioning from the
absolute top. Also fix the start padding of the small clock.

Fixes: 318715303
Test: show small and large clock in flexiglass
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT

Change-Id: I25a37407c6dcfa16c86cbb984745786d87947c5c