libata: move generic hardreset code from sata_sff_hardreset() to sata_link_hardreset()

sata_sff_hardreset() contains link readiness wait logic which isn't
SFF specific.  Move that part into sata_link_hardreset(), which now
takes two more parameters - @online and @check_ready.  Both are
optional.  The former is out parameter for link onlineness after
reset.  The latter is used to wait for link readiness after hardreset.

Users of sata_link_hardreset() is updated to use new funtionality and
ahci_hardreset() is updated to use sata_link_hardreset() instead of
sata_sff_hardreset().  This doesn't really cause any behavior change.

Signed-off-by: Tejun Heo <htejun@gmail.com>

drivers/ata/ata_piix.c

@@ -1022,7 +1022,7 @@ static int piix_sidpr_hardreset(struct ata_link *link, unsigned int *class,
 	int rc;
 
 	/* do hardreset */
-	rc = sata_link_hardreset(link, timing, deadline);
+	rc = sata_link_hardreset(link, timing, deadline, NULL, NULL);
 	if (rc) {
 		ata_link_printk(link, KERN_ERR,
 				"COMRESET failed (errno=%d)\n", rc);