[SCSI] libsas: async ata scanning

libsas ata error handling is already async but this does not help the
scan case.  Move initial link recovery out from under host->scan_mutex,
and delay synchronization with eh until after all port probe/recovery
work has been queued.

Device ordering is maintained with scan order by still calling
sas_rphy_add() in order of domain discovery.

Since we now scan the domain list when invoking libata-eh we need to be
careful to check for fully initialized ata ports.

Acked-by: Jack Wang <jack_wang@usish.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 1fab235..2e26fca 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -105,6 +105,7 @@
 extern struct ata_port *ata_port_alloc(struct ata_host *host);
 extern const char *sata_spd_string(unsigned int spd);
 extern int ata_port_probe(struct ata_port *ap);
+extern void __ata_port_probe(struct ata_port *ap);
 
 /* libata-acpi.c */
 #ifdef CONFIG_ATA_ACPI