Lower dip-barries for using tablet layouts.

7" tablets now default to haveing a split status bar, so lower the
values needed to trigger tablet layout.

port - 912dp (~5.7 in.) now is 879dp (~5.5 in.)
land - 552dp (~3.5 in.) now is 527dp (~3.3 in.)

Calculations were made using the following:

Orientation: Total height - nav bar height - status bar height
Portrait   : 960 - 56 - 25 = 879
Landscape  : 600 - 48 - 25 = 527

Bug: 6382404
Change-Id: Ib2dfa6c9d57a953e614af3a9a22fcdff64fe886f