net: stmmac: Add Ingenic SoCs MAC support.

Add support for Ingenic SoC MAC glue layer support for the stmmac
device driver. This driver is used on for the MAC ethernet controller
found in the JZ4775 SoC, the X1000 SoC, the X1600 SoC, the X1830 SoC,
and the X2000 SoC.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>