ahci: Fix sglist offset manipulation for BE machines

This does not bother DMA, because DMA generally transfers
the entire SGList in one shot if it can.

PIO, on the other hand, tries to transfer just one sector
at a time, and will make multiple visits to the sglist
to fetch memory addresses.

Fix the memory address calculaton when we have an offset
by moving the offset addition OUTSIDE of the le64_to_cpu
calculation.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Andreas Färber <afaerber@suse.de>
Message-id: 1426811056-2202-4-git-send-email-jsnow@redhat.com