ahci: Check and set 64-bit DMA mask for platform AHCI driver

The current platform AHCI driver does not set the dma_mask correctly
for 64-bit DMA capable AHCI controller. This patch checks the AHCI
capability bit and set the dma_mask and coherent_dma_mask accordingly.

Signed-off-by: Suravee Suthikulpanit <[e-mail]>
Reviewed-by: Bartlomiej Zolnierkiewicz <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Tested-by: Hans de Goede <[e-mail]>
Tested-by: Suman Tripathi <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

drivers/ata/libahci_platform.c

···
 			ap->ops = &ata_dummy_port_ops;
 	}
 
+	if (hpriv->cap & HOST_CAP_64) {
+		rc = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(64));
+		if (rc) {
+			rc = dma_coerce_mask_and_coherent(dev,
+							  DMA_BIT_MASK(32));
+			if (rc) {
+				dev_err(dev, "Failed to enable 64-bit DMA.\n");
+				return rc;
+			}
+			dev_warn(dev, "Enable 32-bit DMA instead of 64-bit.\n");
+		}
+	}
+
 	rc = ahci_reset_controller(host);
 	if (rc)
 		return rc;