sd-ndisc,sd-radv: fix use of uninitialized value

When icmp6_receive() fails, then the source address is not initialized yet.

(cherry picked from commit 4674f40)

Author: yuwata

src/libsystemd-network/sd-ndisc.c

@@ -227,8 +227,7 @@ static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userda
 
                 switch (r) {
                 case -EADDRNOTAVAIL:
-                        log_ndisc(nd, "Received RA from non-link-local address %s. Ignoring.",
-                                  IN6_ADDR_TO_STRING(&rt->address));
+                        log_ndisc(nd, "Received RA from non-link-local address. Ignoring.");
                         break;
 
                 case -EMULTIHOP:

src/libsystemd-network/sd-radv.c

@@ -271,8 +271,7 @@ static int radv_recv(sd_event_source *s, int fd, uint32_t revents, void *userdat
 
                 switch (r) {
                 case -EADDRNOTAVAIL:
-                        log_radv(ra, "Received RS from non-link-local address %s. Ignoring",
-                                 IN6_ADDR_TO_STRING(&src));
+                        log_radv(ra, "Received RS from non-link-local address. Ignoring");
                         break;
 
                 case -EMULTIHOP: