libata: reorder functions in libata-sff.c

Reorder functions in drivers/ata/libata-sff.c such that functions
generally follow ops table order and init functions come last.  This
is in preparation of SFF cleanup.

This patch strictly moves stuff around and as such doesn't cause any
functional difference.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>