Read the tx-fifo-depth and rx-fifo-depth from the devicetree. The Synopsys
stmmac controller fifos are configurable per product instance, and the fifo
sizes are needed to configure certain features correctly such as flow control.
Signed-off-by: NVince Bridgers <vbridger@opensource.altera.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>