[libata] sata_nv: disable ADMA by default

Continues to have open issues, and engineering support is extremely difficult
to come by, according to fellow NVIDIA engineers.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index 8bb8ba1..95fd0cd 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -531,7 +531,7 @@
 MODULE_DEVICE_TABLE(pci, nv_pci_tbl);
 MODULE_VERSION(DRV_VERSION);
 
-static int adma_enabled = 1;
+static int adma_enabled;
 static int swncq_enabled = 1;
 
 static void nv_adma_register_mode(struct ata_port *ap)