net: macb: Added support for many RX queues

To be able for packet reception on different RX queues some
configuration has to be performed. This patch checks how many
hardware queue does GEM support and initializes them.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
Signed-off-by: David S. Miller <davem@davemloft.net>