bgpd: Fix graceful restart capability minsize

* bgp_open.c: cap_minsize should be CAPABILITY_CODE_RESTART_LEN for RESTART
  not 6.
diff --git a/bgpd/bgp_open.c b/bgpd/bgp_open.c
index 38d9dc5..23090eb 100644
--- a/bgpd/bgp_open.c
+++ b/bgpd/bgp_open.c
@@ -435,7 +435,7 @@
   [CAPABILITY_CODE_MP]		= CAPABILITY_CODE_MP_LEN,
   [CAPABILITY_CODE_REFRESH]	= CAPABILITY_CODE_REFRESH_LEN,
   [CAPABILITY_CODE_ORF]		= CAPABILITY_CODE_ORF_LEN,
-  [CAPABILITY_CODE_RESTART]	= 6,
+  [CAPABILITY_CODE_RESTART]	= CAPABILITY_CODE_RESTART_LEN,
   [CAPABILITY_CODE_AS4]		= CAPABILITY_CODE_AS4_LEN,
   [CAPABILITY_CODE_DYNAMIC]	= CAPABILITY_CODE_DYNAMIC_LEN,
   [CAPABILITY_CODE_REFRESH_OLD]	= CAPABILITY_CODE_REFRESH_LEN,