networkd-ndisc: do not return value from void function

Fixup for systemd#3304.

Only warn, and not return, because that's what sd_dhcp6_client_start()
does right below the call to sd_dhcp6_client_set_local_address().

Author: keszybz

src/network/networkd-ndisc.c

@@ -159,7 +159,7 @@ static void ndisc_router_handler(sd_ndisc *nd, uint8_t flags, const struct in6_a
 
                 r = sd_dhcp6_client_set_local_address(link->dhcp6_client, &link->ipv6ll_address);
                 if (r < 0 && r != -EBUSY)
-                        return log_link_warning_errno(link, r, "Could not set IPv6LL address in DHCP client: %m");
+                        log_link_warning_errno(link, r, "Could not set IPv6LL address in DHCP client: %m");
 
                 r = sd_dhcp6_client_start(link->dhcp6_client);
                 if (r < 0 && r != -EBUSY)
@@ -209,7 +209,7 @@ static void ndisc_handler(sd_ndisc *nd, int event, void *userdata) {
 
                 r = sd_dhcp6_client_set_local_address(link->dhcp6_client, &link->ipv6ll_address);
                 if (r < 0 && r != -EBUSY)
-                        return log_link_warning_errno(link, r, "Could not set IPv6LL address in DHCP client: %m");
+                        log_link_warning_errno(link, r, "Could not set IPv6LL address in DHCP client: %m");
 
                 r = sd_dhcp6_client_start(link->dhcp6_client);
                 if (r < 0 && r != -EBUSY)