[SPARC64]: Add missing dma_get_cache_alignment().

drivers/infiniband/hw/mthca/mthca_main.c: In function `mthca_init_icm':
drivers/infiniband/hw/mthca/mthca_main.c:468: error: implicit declaration of function `dma_get_cache_alignment'

Pinch the one from asm-generic/dma-mapping.h

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>