net: macb: Add support for Xilinx Zynq SoC

net: macb: Add support for Xilinx Zynq SoC

Although Xilinx Zynq SoC was using MACB similar hardware. However,
U-boot MACB driver was not supporting Xilinx Zynq SoC. This patch is
to add support for the Xilinx Zynq SoC to the existing MACB network
driver.

This patch is to add Zynq GEM DMA Config, provide callback
function for different linkspeed for case of using Xilinx Zynq
Programmable Logic as GMII to RGMII converter.

This patch convert the return value to use error codes.

Signed-off-by: Wilson Lee <wilson.lee@ni.com>
Cc: Chen Yee Chew <chen.yee.chew@ni.com>
Cc: Keng Soon Cheah <keng.soon.cheah@ni.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Wenyou Yang <wenyou.yang@atmel.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>