dma kmalloc handling fixes

1. We need kmalloc_percpu for all of the now extended kmalloc caches
   array not just for each shift value.

2. init_kmem_cache_nodes() must assume node 0 locality for statically
   allocated dma kmem_cache structures even after boot is complete.

Reported-and-tested-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>