ARM: mm: Optimise the v7 Dcache flush all routine.

The current algorithm flushes using the SET and WAY, where it iterates over
a given SET in all the WAYS and to the next SET. Change this so that every
successive flush address will go to in to the alternate EMIF(1/2), there by
utilising the full bandwidth. Also iterating all the SETS of a given WAY,
and then switching to the next way can reduce the possibility of frequent
change in the row bits during successive transactions of the DDR memory.
This will help in reducing the ROW open/close time.

Signed-off-by: Marquette Anderson <m-anderson13@ti.com>