Revert "Revert "mm: add cma pcp list""

This reverts commit f690884e.

Re-enable this patch. Earlier, this was reverted as it exposed
several CMA bugs which are now fixed. So, time to re-enable
this patch.

Original commit text:

Add a cma pcp list in order to increase cma memory utilization.

Increased cma memory utilization will improve overall memory
utilization because free cma pages are ignored when memory reclaim
is done with gfp mask GFP_KERNEL.

Since most memory reclaim is done by kswapd, which uses a gfp mask
of GFP_KERNEL, by increasing cma memory utilization we are therefore
ensuring that less aggressive memory reclaim takes place.

Increased cma memory utilization will improve performance,
for example it will increase app concurrency.

Change-Id: Ia0f555427148b95068b3a7481e695ed02d58710d
Signed-off-by: Liam Mark <lmark@codeaurora.org>