arm: mvebu: turris_omnia: Overwrite ethaddr only if invalid

Currently we always overwrite ethaddrs with those from EEPROM.

In order to allow user to use a cloned MAC address in U-Boot, change the
code so that it sets ethaddr variables only if they aren't set or are
invalid.
Signed-off-by: NMarek Behún <marek.behun@nic.cz>
Reviewed-by: NStefan Roese <sr@denx.de>

board/CZ.NIC/turris_omnia/turris_omnia.c

@@ -518,6 +518,15 @@ static void increment_mac(u8 *mac)
 	}
 }
 
+static void set_mac_if_invalid(int i, u8 *mac)
+{
+	u8 oldmac[6];
+
+	if (is_valid_ethaddr(mac) &&
+	    !eth_env_get_enetaddr_by_index("eth", i, oldmac))
+		eth_env_set_enetaddr_by_index("eth", i, mac);
+}
+
 int misc_init_r(void)
 {
 	int err;
@@ -550,18 +559,11 @@ int misc_init_r(void)
 	mac[4] = mac1[2];
 	mac[5] = mac1[3];
 
-	if (is_valid_ethaddr(mac))
-		eth_env_set_enetaddr("eth1addr", mac);
-
+	set_mac_if_invalid(1, mac);
 	increment_mac(mac);
-
-	if (is_valid_ethaddr(mac))
-		eth_env_set_enetaddr("eth2addr", mac);
-
+	set_mac_if_invalid(2, mac);
 	increment_mac(mac);
-
-	if (is_valid_ethaddr(mac))
-		eth_env_set_enetaddr("ethaddr", mac);
+	set_mac_if_invalid(0, mac);
 
 out:
 	return 0;