arm64: dts: allwinner: A64 Sopine: phy-mode rgmii-id

Since commit bbc4d71d ("net: phy: realtek: fix rtl8211e rx/tx
delay config") iSCSI booting fails on the Pine A64 LTS.

This patch changes the phy-mode to use internal delays both for RX and TX
as has been done for other boards affected by the same commit.

Fixes: bbc4d71d ("net: phy: realtek: fix rtl8211e rx/tx delay config")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20201129162627.1244808-1-xypron.glpk@gmx.de