cxgb3 uses dma_alloc_coherent() et al. thus needs linux/dma-mapping.h
include in order to build reliably.

Noticed on sparc64.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NSteve Wise <swise@opengridcomputing.com>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>