[PATCH] ata_piix: rename PIIX_FLAG_IGN_PRESENT to PIIX_FLAG_IGNORE_PCS

Rename PIIX_FLAG_IGN_PRESENT to PIIX_FLAG_IGNORE_PCS as Jeff
requested.

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