niu: Fix warnings due to -Wunused-but-set-variable

Most of these were legitimate, and once case was a real bug
(not propagating errors from ->xcvr_init() methods).

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/niu.c b/drivers/net/niu.c
index 9e6330b..3fa1e9c 100644
--- a/drivers/net/niu.c
+++ b/drivers/net/niu.c
@@ -1233,7 +1233,7 @@
 
 	bmsr = err;
 	if (bmsr & BMSR_LSTATUS) {
-		u16 adv, lpa, common, estat;
+		u16 adv, lpa;
 
 		err = mii_read(np, np->phy_addr, MII_ADVERTISE);
 		if (err < 0)
@@ -1245,12 +1245,9 @@
 			goto out;
 		lpa = err;
 
-		common = adv & lpa;
-
 		err = mii_read(np, np->phy_addr, MII_ESTATUS);
 		if (err < 0)
 			goto out;
-		estat = err;
 		link_up = 1;
 		current_speed = SPEED_1000;
 		current_duplex = DUPLEX_FULL;
@@ -1650,7 +1647,7 @@
 		break;
 	}
 
-	return 0;
+	return err;
 }
 
 static int mii_reset(struct niu *np)
@@ -2381,17 +2378,14 @@
 	struct niu_link_config *lp = &np->link_config;
 	unsigned long ctrl_reg, test_cfg_reg, pll_cfg, i;
 	u64 ctrl_val, test_cfg_val, sig, mask, val;
-	u64 reset_val;
 
 	switch (np->port) {
 	case 0:
-		reset_val =  ENET_SERDES_RESET_0;
 		ctrl_reg = ENET_SERDES_0_CTRL_CFG;
 		test_cfg_reg = ENET_SERDES_0_TEST_CFG;
 		pll_cfg = ENET_SERDES_0_PLL_CFG;
 		break;
 	case 1:
-		reset_val =  ENET_SERDES_RESET_1;
 		ctrl_reg = ENET_SERDES_1_CTRL_CFG;
 		test_cfg_reg = ENET_SERDES_1_TEST_CFG;
 		pll_cfg = ENET_SERDES_1_PLL_CFG;
@@ -8135,7 +8129,7 @@
 	netif_printk(np, probe, KERN_DEBUG, np->dev,
 		     "VPD_SCAN: start[%x] end[%x]\n", start, end);
 	while (start < end) {
-		int len, err, instance, type, prop_len;
+		int len, err, prop_len;
 		char namebuf[64];
 		u8 *prop_buf;
 		int max_len;
@@ -8151,8 +8145,6 @@
 		len = err;
 		start += 3;
 
-		instance = niu_pci_eeprom_read(np, start);
-		type = niu_pci_eeprom_read(np, start + 3);
 		prop_len = niu_pci_eeprom_read(np, start + 4);
 		err = niu_pci_vpd_get_propname(np, start + 5, namebuf, 64);
 		if (err < 0)