parisc: use asm-generic/scatterlist.h

parisc uses iova and iova_length in scatterlist structure instead of
dma_address and dma_length.  However, the accessor are used so we can
convert parisc to use asm-generic/scatterlist.h easily.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>