Fix possible skb_over_panic event in Freescale's "gianfar" driver. 

The skb_over_panic occurs due to calling skb_put() within 
gfar_clean_rx_ring(). This happens if (and only if) shortly prior to the 
event and a few lined above the skb_put(), an skb was queued back to the 
priv->rx_recycle queue due to RXBD_LAST or RXBD_ERR status.
The skb is queued without properly re-setting its state.

The patch properly reset the skb state.

I have tested this patch on MPC8548 based product and asserted it avoided the skb_over_panic event.

Signed-off-by: Eran Liberty <liberty@extricom.com>

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