[PATCH] [libata] some function renaming

s/ata_host_add/ata_port_add/
s/ata_host_init/ata_port_init/

libata naming got stuck in the middle of a Great Renaming:

	ata_host -> ata_port
	ata_host_set -> ata_host

To eliminate confusion, let's just give up for now, and simply ensure
that things are internally consistent.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Tejun Heo <htejun@gmail.com>