sata_mv: Support SoC controllers

Marvell's Orion SoC includes SATA controllers based on Marvell's
PCI-to-SATA 88SX controllers. This patch extends the libATA sata_mv
driver to support those controllers.

[edited to use linux/ata_platform.h -jg]

Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>