udp: Use link up/down signals from the MIB for the link

The mib was patched to send link up/down in case of failures,
only put a link service when the MIB tells us the link is
up, the failure case should only happen for remote links
failing. We will reset and go through link alignment.
diff --git a/include/udp_input.h b/include/udp_input.h
index 2d84fef..7c95384 100644
--- a/include/udp_input.h
+++ b/include/udp_input.h
@@ -38,6 +38,9 @@
 #define UDP_DATA_RETR_PRIO_3	19
 #define UDP_DATA_RETR_COMPL	32
 #define UDP_DATA_RETR_IMPOS	33
+#define UDP_DATA_LINK_UP	34
+#define UDP_DATA_LINK_DOWN	35
+
 
 struct udp_data_hdr {
 	uint8_t format_type;