tg3: cleanup an error path in tg3_phy_reset_5703_4_5()

In the original code, if tg3_readphy() fails then it does an unnecessary
check to verify "err" is still zero and then returns -EBUSY.

My static checker complains about the unnecessary "if (!err)" check and
anyway it is better to propagate the -EBUSY error code from
tg3_readphy() instead of hard coding it here.  And really the original
code is confusing to look at.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Nithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -2609,13 +2609,14 @@ static int tg3_phy_reset_5703_4_5(struct tg3 *tp)
 
 	tg3_writephy(tp, MII_CTRL1000, phy9_orig);
 
-	if (!tg3_readphy(tp, MII_TG3_EXT_CTRL, &reg32)) {
+	err = tg3_readphy(tp, MII_TG3_EXT_CTRL, &reg32);
+	if (err)
+		return err;
+
 	reg32 &= ~0x3000;
 	tg3_writephy(tp, MII_TG3_EXT_CTRL, reg32);
-	} else if (!err)
-		err = -EBUSY;
 
-	return err;
+	return 0;
 }
 
 static void tg3_carrier_off(struct tg3 *tp)