FRV: move DMA macros to scatterlist.h for consistency.

To be consistent with other architectures, these two DMA macros should
be defined in scatterlist.h as opposed to dma-mapping.h

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>