Add support for configuring queueMaxSDU. As DWMAC IPs doesn't support
queueMaxSDU table handle this in the SW. The maximum 802.3 frame size
that is allowed to be transmitted by any queue is queueMaxSDU +
16 bytes (i.e. 6 bytes SA + 6 bytes DA + 4 bytes FCS).

Inspired from intel i225 driver.
Signed-off-by: Rohan G Thomas <rohan.g.thomas@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>