netxen: clean up firmware version checks

NX2031 firmware version will never be > 4.0.0, so replace
(adapter->fw_major < 4) checks with pci revision ID check.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/netxen/netxen_nic_init.c b/drivers/net/netxen/netxen_nic_init.c
index 9135845..ef7f1b1 100644
--- a/drivers/net/netxen/netxen_nic_init.c
+++ b/drivers/net/netxen/netxen_nic_init.c
@@ -1477,7 +1477,7 @@
 		NXWR32(adapter, rds_ring->crb_rcv_producer,
 				(producer-1) & (rds_ring->num_desc-1));
 
-		if (adapter->fw_major < 4) {
+		if (NX_IS_REVISION_P2(adapter->ahw.revision_id)) {
 			/*
 			 * Write a doorbell msg to tell phanmon of change in
 			 * receive ring producer