Ethernet PHY on BananaPi M2 Ultra provides RX and TX delays. Fix
ethernet node to reflect that fact.

Fixes: c36fd5a4 ("ARM: dts: sun8i: r40: bananapi-m2-ultra: Enable GMAC ethernet controller")
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20201025081949.783443-1-jernej.skrabec@siol.net