libata: fix timing computation in ata_eh_reset()

As jiffies changes asynchronously, it needs to be cached if unchanging
timestamp is needed.  The code in ata_eh_reset() intended to do that
with @now but never actually did it.  Fix it.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-eh.c

@@ -2204,7 +2204,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
 		unsigned long now = jiffies;
 
 		if (time_before(now, deadline)) {
-			unsigned long delta = deadline - jiffies;
+			unsigned long delta = deadline - now;
 
 			ata_link_printk(link, KERN_WARNING, "reset failed "
 				"(errno=%d), retrying in %u secs\n",