Make link mode case independent

The link mode is printed in upper case, and following the general
rule that ip command output should work on input, allow either case.

ip/iplink.c

@@ -134,9 +134,9 @@ struct link_util *get_link_kind(const char *id)
 
 int get_link_mode(const char *mode)
 {
-	if (strcmp(mode, "default") == 0)
+	if (strcasecmp(mode, "default") == 0)
 		return IF_LINK_MODE_DEFAULT;
-	if (strcmp(mode, "dormant") == 0)
+	if (strcasecmp(mode, "dormant") == 0)
 		return IF_LINK_MODE_DORMANT;
 	return -1;
 }
@@ -433,7 +433,7 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 		} else if (strcmp(*argv, "mode") == 0) {
 			int mode;
 			NEXT_ARG();
-			mode =  get_link_mode(*argv);
+			mode = get_link_mode(*argv);
 			if (mode < 0)
 				invarg("Invalid link mode\n", *argv);
 			addattr8(&req->n, sizeof(*req), IFLA_LINKMODE, mode);