staging: et131x: use netif_rx_ni() for packet receive

netif_rx is meant to be called from interrupts because it doesn't wake
up ksoftirqd.  For calling from outside interrupts, netif_rx_ni exists.

This stops the error "NOHZ: local_softirq_panding 08" that happens on
some machines with NOHZ and plip --- it is caused by the fact that
softirq is pending and ksoftirqd is sleeping.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>