According to the R-Car Gen3 Hardware Manual Errata for Rev 1.00 of
August 24, 2018, the TX clock internal Delay mode does'nt support
on R-Car D3. This patch fixes EthernetAVB phy mode to rgmii.

This is achieved by simply dropping the phy-mode property from
r8a77995-draak.dts as the default property for this for r8a77995,
as set in r8a77995.dtsi, is "rgmii".
Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Tested-by: Ulrich Hecht <uli+renesas@fpond.eu>