driver: net: cpsw: add support for RGMII id mode support and RMII clock source selection

cpsw driver supports only selection of phy mode in control module
but control module has more setting like RGMII ID mode selection,
RMII clock source selection. So ported to cpsw-phy-sel driver
from kernel to u-boot.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>