phy: atheros: add support for RGMII_ID, RGMII_TXID and RGMII_RXID
This adds support for internal delay on RX and TX on RGMII interface for the
AR8035 phy.
This is basically the same Linux driver do. Tested on a Zynq Zturn board (for
which u-boot support in is my tree; first patch waiting ML approval)
Signed-off-by: Andrea Merello <andrea.merello@gmail.com> Reviewed-by: Marek Vasut <marex@denx.de> Acked-by: Marek Vasut <marex@denx.de> Acked-by: Joe Hershberger <joe.hershberger@ni.com>