sparc: merge 32-bit and 64-bit version of pci.h

There are enough common defintions that a single header seems nicer.

Also drop the pointless <linux/dma-mapping.h> include.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Sam Ravnborg <sam@ravnborg.org>