via-rhine: VTunknown1 device is really VT8251 South Bridge

The VIA Technologies VT8251 South Bridge's integrated Rhine-II
Ethernet MAC comes has a PCI revision value of 0x7c.  This was
verified on ASUS P5V800-VM mainboard.
Signed-off-by: Kevin Brace <kevinbrace@bracecomputerlab.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/via/via-rhine.c

@@ -243,7 +243,7 @@ enum rhine_revs {
 	VT8233		= 0x60,	/* Integrated MAC */
 	VT8235		= 0x74,	/* Integrated MAC */
 	VT8237		= 0x78,	/* Integrated MAC */
-	VTunknown1	= 0x7C,
+	VT8251		= 0x7C,	/* Integrated MAC */
 	VT6105		= 0x80,
 	VT6105_B0	= 0x83,
 	VT6105L		= 0x8A,