babeld: add MP-specific zclient API fix

Add proper initialization of SAFI field, which is present in the
revisions of zapi_ipv4 and zapi_ipv6 structures specific to
MP-BGP patchset. Without this change no Babel routes could make
into zebra RIB.
diff --git a/babeld/kernel_zebra.c b/babeld/kernel_zebra.c
index 7ddc797..53da5f4 100644
--- a/babeld/kernel_zebra.c
+++ b/babeld/kernel_zebra.c
@@ -206,6 +206,7 @@
     api.type  = ZEBRA_ROUTE_BABEL;
     api.flags = 0;
     api.message = 0;
+    api.safi = SAFI_UNICAST;
     SET_FLAG(api.message, ZAPI_MESSAGE_NEXTHOP);
     api.nexthop_num = 1;
     api.nexthop = &nexthop_pointer;
@@ -248,6 +249,7 @@
     api.type  = ZEBRA_ROUTE_BABEL;
     api.flags = 0;
     api.message = 0;
+    api.safi = SAFI_UNICAST;
     SET_FLAG(api.message, ZAPI_MESSAGE_NEXTHOP);
     api.nexthop_num = 1;
     api.nexthop = &nexthop_pointer;
@@ -291,6 +293,7 @@
     api.type  = ZEBRA_ROUTE_BABEL;
     api.flags = 0;
     api.message = 0;
+    api.safi = SAFI_UNICAST;
     SET_FLAG(api.message, ZAPI_MESSAGE_NEXTHOP);
     api.nexthop_num = 1;
     api.nexthop = &nexthop_pointer;
@@ -334,6 +337,7 @@
     api.type  = ZEBRA_ROUTE_BABEL;
     api.flags = 0;
     api.message = 0;
+    api.safi = SAFI_UNICAST;
     SET_FLAG(api.message, ZAPI_MESSAGE_NEXTHOP);
     api.nexthop_num = 1;
     api.nexthop = &nexthop_pointer;