dma-mapping-fast: add support for atomic fastmap allocations

Support for coherent and non-coherent atomic allocations
in fastmap.

Change-Id: I3628508a4b2af5aa82d56a4a6a6ee4cef98cd47f
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
[isaacm@codeaurora.org: Leverage atomic DMA pool framework code]
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>