ixgbe: make ixgbe_led_on/off_t_x550em static

These functions are only used in ixgbe_x550.c.

Fixes a warning when compiling with -Wmissing-prototypes
Reported-by: NKrishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: NEmil Tantilov <emil.s.tantilov@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c

@@ -2125,7 +2125,7 @@ static s32 ixgbe_reset_phy_t_X550em(struct ixgbe_hw *hw)
  *  @hw: pointer to hardware structure
  *  @led_idx: led number to turn on
  **/
-s32 ixgbe_led_on_t_x550em(struct ixgbe_hw *hw, u32 led_idx)
+static s32 ixgbe_led_on_t_x550em(struct ixgbe_hw *hw, u32 led_idx)
 {
 	u16 phy_data;
 
@@ -2147,7 +2147,7 @@ s32 ixgbe_led_on_t_x550em(struct ixgbe_hw *hw, u32 led_idx)
  *  @hw: pointer to hardware structure
  *  @led_idx: led number to turn off
  **/
-s32 ixgbe_led_off_t_x550em(struct ixgbe_hw *hw, u32 led_idx)
+static s32 ixgbe_led_off_t_x550em(struct ixgbe_hw *hw, u32 led_idx)
 {
 	u16 phy_data;