Cris: convert to using generic dma-coherent mem allocator

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>