Fix 6486099: Fix clipping issues with MultiWaveView on phone/tablet

This fixes a problem where the bounds of the view weren't being
calculated properly when a separate outer radius was specified.

The code now takes the maximum of the ring drawable's width/height
and that specified in the resource files.

This gives it the best default look on all devices while still
allowing minor tweaks.

Change-Id: I5daa40ff4f14653c8cc89b39102816afb976e4f7