Optimize the bakery lock structure for coherent memory

Optimize the bakery lock structure for coherent memory

This patch optimizes the data structure used with the bakery lock
implementation for coherent memory to save memory and minimize memory
accesses. These optimizations were already part of the bakery lock
implementation for normal memory and this patch now implements
it for the coherent memory implementation as well. Also
included in the patch is a cleanup to use the do-while loop while
waiting for other contenders to finish choosing their tickets.

Change-Id: Iedb305473133dc8f12126726d8329b67888b70f1