net: natsemi: Remove set but not used variable

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

drivers/net/ethernet/natsemi/ns83820.c: In function ns83820_get_link_ksettings:
drivers/net/ethernet/natsemi/ns83820.c:1210:11: warning: variable ‘tanar’ set but not used [-Wunused-but-set-variable]

`tanar` is never used, so remove it.
Signed-off-by: NZheng Yongjun <zhengyongjun3@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/natsemi/ns83820.c

@@ -1204,7 +1204,7 @@ static int ns83820_get_link_ksettings(struct net_device *ndev,
 				      struct ethtool_link_ksettings *cmd)
 {
 	struct ns83820 *dev = PRIV(ndev);
-	u32 cfg, tanar, tbicr;
+	u32 cfg, tbicr;
 	int fullduplex   = 0;
 	u32 supported;
 
@@ -1223,7 +1223,7 @@ static int ns83820_get_link_ksettings(struct net_device *ndev,
 
 	/* read current configuration */
 	cfg   = readl(dev->base + CFG) ^ SPDSTS_POLARITY;
-	tanar = readl(dev->base + TANAR);
+	readl(dev->base + TANAR);
 	tbicr = readl(dev->base + TBICR);
 
 	fullduplex = (cfg & CFG_DUPSTS) ? 1 : 0;