[NETPOLL]: pre-fill skb pool

we could do one thing (see the patch below): i think it would be useful 
to fill up the netlogging skb queue straight at initialization time.  
Especially if netpoll is used for dumping alone, the system might not be 
in a situation to fill up the queue at the point of crash, so better be 
a bit more prepared and keep the pipeline filled.

[ I've modified this to be called earlier - mpm ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>