Fix adb am display-size.

There were several problems resulting from the use of
mDefaultDisplay before displayReady() was called.
As it happens, we don't need mDefaultDisplay becase we
can get the information from the default display content.

Also modified the Configuration calculations to never
choose a SQUARE orientation.  The constant is deprecated
and documented as no longer used, so we should make that
be the case.

Change-Id: I326ed7100030a81e24411e898e5243f28895ea22