drivers/net/e1000e: fix sparse warning: Should it be static?

Impact: Make symbol static.

Fix this sparse warning:
  drivers/net/e1000e/82571.c:1229:5: warning: symbol 'e1000_check_for_serdes_link_82571' was not declared. Should it be static?
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/e1000e/82571.c

@@ -1226,7 +1226,7 @@ static s32 e1000_setup_fiber_serdes_link_82571(struct e1000_hw *hw)
  *  Checks for link up on the hardware.  If link is not up and we have
  *  a signal, then we need to force link up.
  **/
-s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
+static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
 {
 	struct e1000_mac_info *mac = &hw->mac;
 	u32 rxcw;