igc: Remove set but not used variables 'ctrl_ext, link_mode'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/ethernet/intel/igc/igc_base.c: In function 'igc_init_phy_params_base':
drivers/net/ethernet/intel/igc/igc_base.c:240:6: warning:
 variable 'ctrl_ext' set but not used [-Wunused-but-set-variable]
  u32 ctrl_ext;

drivers/net/ethernet/intel/igc/igc_base.c: In function 'igc_get_invariants_base':
drivers/net/ethernet/intel/igc/igc_base.c:290:6: warning:
 variable 'link_mode' set but not used [-Wunused-but-set-variable]
  u32 link_mode = 0;

It never used since introduction in
commit c0071c7a ("igc: Add HW initialization code")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igc/igc_base.c

@@ -237,7 +237,6 @@ static s32 igc_init_phy_params_base(struct igc_hw *hw)
 {
 	struct igc_phy_info *phy = &hw->phy;
 	s32 ret_val = 0;
-	u32 ctrl_ext;
 
 	if (hw->phy.media_type != igc_media_type_copper) {
 		phy->type = igc_phy_none;
@@ -247,8 +246,6 @@ static s32 igc_init_phy_params_base(struct igc_hw *hw)
 	phy->autoneg_mask	= AUTONEG_ADVERTISE_SPEED_DEFAULT_2500;
 	phy->reset_delay_us	= 100;
 
-	ctrl_ext = rd32(IGC_CTRL_EXT);
-
 	/* set lan id */
 	hw->bus.func = (rd32(IGC_STATUS) & IGC_STATUS_FUNC_MASK) >>
 			IGC_STATUS_FUNC_SHIFT;
@@ -287,8 +284,6 @@ static s32 igc_init_phy_params_base(struct igc_hw *hw)
 static s32 igc_get_invariants_base(struct igc_hw *hw)
 {
 	struct igc_mac_info *mac = &hw->mac;
-	u32 link_mode = 0;
-	u32 ctrl_ext = 0;
 	s32 ret_val = 0;
 
 	switch (hw->device_id) {
@@ -302,9 +297,6 @@ static s32 igc_get_invariants_base(struct igc_hw *hw)
 
 	hw->phy.media_type = igc_media_type_copper;
 
-	ctrl_ext = rd32(IGC_CTRL_EXT);
-	link_mode = ctrl_ext & IGC_CTRL_EXT_LINK_MODE_MASK;
-
 	/* mac initialization and operations */
 	ret_val = igc_init_mac_params_base(hw);
 	if (ret_val)