gianfar: Fix a filer bug

We need to enable filer whenever we need to use multiple RX
queues. Also, need to program RIR0 register with the required
distribution we require, if using RX filer hashing support for
packet distribution to multiple queues.

Signed-off-by: Sandeep Gopalpet <Sandeep.Kumar@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>