Replace combined mode handling via PIIX_COMB/COMB_PATA_P0 with proper
port map. PIIX now prints port configuration during initialization.
ATA_FLAG_SLAVE_POSS is now turned on for SATA ports only when the
slave device is actually avaliable.
Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>