[PARISC] Create shared <asm/ropes.h> header

Pull out struct sba_device and struct lba_device into a
common ropes.h header. Also fold the parisc portion of
iosapic.h into this file. (Then delete the useless portion
of iosapic.h)

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>