net: netcp: extract eflag from desc for rx_hook handling

Extract the eflag bits from the received desc and pass it down
the rx_hook chain to be available for netcp modules. Also the
psdata and epib data has to be inspected by the netcp modules.
So the desc can be freed only after returning from the rx_hook.
So move knav_pool_desc_put() after the rx_hook processing.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>