ata: make the ata_piix driver using new SATA framework

original ata_piix driver is using IDE framework, not real
SATA framework. For now, the ata_piix driver is only used
by x86 sc520_cdp board. This patch makes the ata_piix driver
use the new SATA framework, so

- remove the duplicated command stuff
- remove the CONFIG_CMD_IDE define in the sc520_cdp.h
- add the CONFIG_CMD_SATA define to sc520_cdp.h

Signed-off-by: Dave Liu <daveliu@freescale.com>
diff --git a/drivers/block/ata_piix.h b/drivers/block/ata_piix.h
index bb1acb3..ed2e4d5 100644
--- a/drivers/block/ata_piix.h
+++ b/drivers/block/ata_piix.h
@@ -82,11 +82,9 @@
 /************DRIVER SPECIFIC DEFINITIONS AND DECLARATIONS**************/
 
 #ifdef DRV_DECL			/*Driver specific declaration */
-int init_sata (void);
+int init_sata (int dev);
 #endif
 
 #ifdef DRV_DECL			/*Defines Driver Specific variables */
 struct sata_port port[CFG_SATA_MAXBUS];
-block_dev_desc_t sata_dev_desc[CFG_SATA_MAXDEVICES];
-int curr_dev = -1;
 #endif