addons: vrf: fix check for max vrf dev count

Ticket: CM-10465
Reviewed By: julien, nikhil
Testing Done: Tested creating more than 64 vrf devices

example config:
{noformat}
%for v in range(1, 66):
auto vrf${v}
iface vrf${v}
        vrf-table auto
%endfor
{noformat}

also, since vrf module already does a link up on vrf dev, remove
link up of vrf dev from ifupdownmain scheduler callback

ifupdown/ifupdownmain.py

@@ -112,6 +112,8 @@ class ifupdownMain(ifupdownBase):
         # there is no real interface behind it
         if ifaceobj.type == ifaceType.BRIDGE_VLAN:
             return
+        if ifaceobj.link_kind & ifaceLinkKind.VRF:
+            return
         if (ifaceobj.addr_method and
             ifaceobj.addr_method == 'manual'):
             return