netxen: fix register usage

o For NX3031, MSI_MODE, CAPABILITIES_FW and SCRATCHPAD registers
  are obsolete. These register addresses can be used for different
  purpose.

Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/netxen/netxen_nic_ethtool.c b/drivers/net/netxen/netxen_nic_ethtool.c
index aecba78..20f7c58 100644
--- a/drivers/net/netxen/netxen_nic_ethtool.c
+++ b/drivers/net/netxen/netxen_nic_ethtool.c
@@ -632,6 +632,9 @@
 	if ((data_read & 0xffff) != adapter->pdev->vendor)
 		return 1;
 
+	if (NX_IS_REVISION_P3(adapter->ahw.revision_id))
+		return 0;
+
 	data_written = (u32)0xa5a5a5a5;
 
 	NXWR32(adapter, CRB_SCRATCHPAD_TEST, data_written);