lib: fix false context information for SRv6 route

The seg6local route dumped by 'show ipv6 route' makes think that the USP
flavor is supported, whereas it is not the case. This information is a
context information, and for End, the context information should be
empty.

> # show ipv6 route
> [..]
> I>* fc00:0:4::/128 [115/0] is directly connected, sr0, seg6local End USP, weight 1, 00:49:01

Fix this by suppressing the USP information from the output.

Fixes: e496b42 ("bgpd: prefix-sid srv6 l3vpn service tlv")
Signed-off-by: Philippe Guibert <[email protected]>
(cherry picked from commit 658bf02)

lib/srv6.c

@@ -76,7 +76,6 @@ void seg6local_context2json(const struct seg6local_context *ctx,
 {
 	switch (action) {
 	case ZEBRA_SEG6_LOCAL_ACTION_END:
-		json_object_boolean_add(json, "USP", true);
 		return;
 	case ZEBRA_SEG6_LOCAL_ACTION_END_X:
 	case ZEBRA_SEG6_LOCAL_ACTION_END_DX6:
@@ -116,7 +115,7 @@ const char *seg6local_context2str(char *str, size_t size,
 	switch (action) {
 
 	case ZEBRA_SEG6_LOCAL_ACTION_END:
-		snprintf(str, size, "USP");
+		snprintf(str, size, "-");
 		return str;
 
 	case ZEBRA_SEG6_LOCAL_ACTION_END_X: