libata: skip debounce delay on link resume

The link resume logic uses a 200msec delay while debouncing
the SControl register. The rationale behind that delay is
to accommodate some PHYs that behave badly if their SStatus/
SControl registers are pounded immediately on resume.
The Broadcom STB SATA PHY does not seem to have this issue.
This patch introduces a new link flag that allows platforms
to skip the debounce delay if it isn't needed.

Signed-off-by: Danesh Petigara <dpetigara@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index f5ae6f4..cbb7471 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -3598,7 +3598,8 @@
 		 * immediately after resuming.  Delay 200ms before
 		 * debouncing.
 		 */
-		ata_msleep(link->ap, 200);
+		if (!(link->flags & ATA_LFLAG_NO_DB_DELAY))
+			ata_msleep(link->ap, 200);
 
 		/* is SControl restored correctly? */
 		if ((rc = sata_scr_read(link, SCR_CONTROL, &scontrol)))