iproute2: Fix typo in get_prefix_1()

Fixes a typo in get_prefix_1() which broke the prefix default
names { default | any | all }.

The most obvious fallout from this bug was:

	$ ip route add default via 1.1.1.1
	Error: an inet prefix is expected rather than "default".

Fixes: dacc5d41 ("add basic mpls support to iproute")
Signed-off-by: Thomas Graf <tgraf@suug.ch>

lib/utils.c

@@ -496,7 +496,7 @@ int get_prefix_1(inet_prefix *dst, char *arg, int family)
 	if (strcmp(arg, "default") == 0 ||
 	    strcmp(arg, "any") == 0 ||
 	    strcmp(arg, "all") == 0) {
-		if ((family == AF_DECnet) || (family = AF_MPLS))
+		if ((family == AF_DECnet) || (family == AF_MPLS))
 			return -1;
 		dst->family = family;
 		dst->bytelen = 0;