e1000e: use alternate MAC address on ESB2 if available

Similar to 82571/2/3 parts that already do this, if ESB2/80003es2lan parts
have an alternate MAC address provided in the EEPROM use it instead of the
default MAC address.  This patch makes the the actual code that does this
generic so that it can be better used by both MAC families.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/e1000e/defines.h b/drivers/net/e1000e/defines.h
index e02e382..db05ec3 100644
--- a/drivers/net/e1000e/defines.h
+++ b/drivers/net/e1000e/defines.h
@@ -460,6 +460,8 @@
  */
 #define E1000_RAR_ENTRIES     15
 #define E1000_RAH_AV  0x80000000        /* Receive descriptor valid */
+#define E1000_RAL_MAC_ADDR_LEN 4
+#define E1000_RAH_MAC_ADDR_LEN 2
 
 /* Error Codes */
 #define E1000_ERR_NVM      1