[PATCH] ata_piix: strip now unneded MAP related stuff

Now that PCS isn't used for device detection anymore...

* esb_sata is identical to ich5_sata
* no reason to know present_shift
* no reason to store map_db in host private area

The MAP table itself is left because it can be used for SCR access.

Signed-off-by: Jeff Garzik <jeff@garzik.org>