ipv6: Remove extra counter pull before gc

Per cpu entries are no longer used in consideration
for doing gc or not. Remove the extra per cpu entries
pull to directly check for time and perform gc.

Signed-off-by: Tanmay Bhushan <007047221b@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>