net: phy: realtek: add rx delay support for RTL8211F

Add RX delay enable support for RTL8211F PHY.

Reviewed-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>