net: ucc_geth, increase no. of HW RX descriptors

In a busy network we see ucc_geth is dropping RX pkgs every now
and then. Increase the RX queues HW descriptors from
16 to 32 to deal with this.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: David S. Miller <davem@davemloft.net>