libata: Add H2D FIS "auxiliary" port flag

Add a new port flag, ATA_FLAG_FPDMA_AUX, used to indicate
support for transmission of the H2D FIS 'auxiliary' field.

Signed-off-by: Marc Carino <marc.ceeeee@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 5064f3e..8d41c57 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1288,6 +1288,14 @@
 		 */
 		if (!(hpriv->flags & AHCI_HFLAG_NO_FPDMA_AA))
 			pi.flags |= ATA_FLAG_FPDMA_AA;
+
+		/*
+		 * All AHCI controllers should be forward-compatible
+		 * with the new auxiliary field. This code should be
+		 * conditionalized if any buggy AHCI controllers are
+		 * encountered.
+		 */
+		pi.flags |= ATA_FLAG_FPDMA_AUX;
 	}
 
 	if (hpriv->cap & HOST_CAP_PMP)