drivers/net/ethernet/via/via-velocity.c: update napi implementation

Drivers supporting NAPI should use a NAPI-specific function for receiving
packets.  Hence netif_rx is changed to netif_receive_skb.

Furthermore netif_napi_del should be used in the probe and remove function
to clean up the NAPI resource information.

Thanks to Francois Romieu, David Shwatrz and Rami Rosen for their help on
this patch.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>