net: fec: add imx8mq and imx8qm new versions support

The ENET of imx8mq and imx8qm are basically the same as imx6sx,
but they have new features support based on imx6sx, like:
- imx8mq: supports IEEE 802.3az EEE standard.
- imx8qm: supports RGMII mode delayed clock.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>