libata: report link resume failure as KERN_WARNING instead of ERR

Link resume failure in itself isn't an error condition and may happen
regularly depending on hardware configuration.  Reporting it as
KERN_ERR makes the condition unnecessarily prominent (e.g. reported
during boot).  Use KERN_WARNING instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: David Shaw <dshaw@jabberwocky.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/ata/libata-core.c

@@ -3534,7 +3534,7 @@ int sata_link_resume(struct ata_link *link, const unsigned long *params,
 	} while ((scontrol & 0xf0f) != 0x300 && --tries);
 
 	if ((scontrol & 0xf0f) != 0x300) {
-		ata_link_err(link, "failed to resume link (SControl %X)\n",
+		ata_link_warn(link, "failed to resume link (SControl %X)\n",
 			     scontrol);
 		return 0;
 	}