ahci: move ahci_sb600_softreset to libahci.c and rename it

ahci_sb600_softreset was in ahci.c. This function is used
to fix soft reset failure and renames as ahci_pmp_retry_softreset
in libahci.c.

Signed-off-by: Yuan-Hsin Chen <yhchen@faraday-tech.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/ata/ahci.h

@@ -312,6 +312,7 @@ extern struct device_attribute *ahci_sdev_attrs[];
 	.sdev_attrs		= ahci_sdev_attrs
 
 extern struct ata_port_operations ahci_ops;
+extern struct ata_port_operations ahci_pmp_retry_srst_ops;
 
 void ahci_fill_cmd_slot(struct ahci_port_priv *pp, unsigned int tag,
 			u32 opts);