net/phy: refactor RTL8211F initialization

RTL8211F needs to enalbe TXDLY for RGMII during
phy initialization, so move it to rtl8211f_config
for early initialization.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
cc: Joe Hershberger <joe.hershberger@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>