Update InCallUI for "generic" conference calls.

+ Use the newer "phone" asset (same as emergency calls).
+ Add xxxhdpi phone asset.
- Remove unused assets.
+ Tint the subscription icon properly in secondary call info.
+ Reorganize listeners in CallCardFragment to be less
redundant, and so FAB is properly positioned above the secondary
call info.

Bug: 17581379
Change-Id: Id4f1c1659ab8c17313cdd0393be51954b5cd449a