zebra: zebra route-map delay-timer is global not per vrf

zebra: zebra route-map delay-timer is global not per vrf

The zebra route-map delay timer value is a global value
not a per vrf change.  As such we should only print it
out one time.

We are seeing this:

zebra route-map delay-timer 33
 exit-vrf
zebra route-map delay-timer 33

When we have 2 vrf's configured.

Fix the code to only write it out for the default vrf

Ticket: CM-32888
Signed-off-by: Donald Sharp <sharpd@nvidia.com>