[PATCH net-next] igc: Remove set but not used variable 'pci_using_dac'

[YueHaibing]

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

drivers/net/ethernet/intel/igc/igc_main.c: In function 'igc_probe':
drivers/net/ethernet/intel/igc/igc_main.c:3535:11: warning:
 variable 'pci_using_dac' set but not used [-Wunused-but-set-variable]

It never used since introduction in commit
d89f88419f99 ("igc: Add skeletal frame for Intel(R) 2.5G Ethernet Controller 
support")

Signed-off-by: YueHaibing <yuehaib...@huawei.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c 
b/drivers/net/ethernet/intel/igc/igc_main.c
index 9d85707..06a4afbe 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -3532,19 +3532,16 @@ static int igc_probe(struct pci_dev *pdev,
        struct net_device *netdev;
        struct igc_hw *hw;
        const struct igc_info *ei = igc_info_tbl[ent->driver_data];
-       int err, pci_using_dac;
+       int err;
 
        err = pci_enable_device_mem(pdev);
        if (err)
                return err;
 
-       pci_using_dac = 0;
        err = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
        if (!err) {
                err = dma_set_coherent_mask(&pdev->dev,
                                            DMA_BIT_MASK(64));
-               if (!err)
-                       pci_using_dac = 1;
        } else {
                err = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
                if (err) {