Fix computation of configuration screen size in dp

FloatingActionButton relies on those dimensions to figure out whether to
display in normal or mini mode when size is auto.

Bug: 110919934
Test: Tested from Studio
Change-Id: Ib1a72d11386e21be2e4064639be0e7c2986f271b
(cherry picked from commit be0ece1ee5e6d9e85e1fb9ad9bc2381e87544ee3)