arm64: dts: meson: remove extra tab from ODROID N2/N2+ ext_mdio node

Remove an extra tab from the ext_mdio node in the ODROID N2/N2+ common
dtsi file.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20210407042609.9736-2-christianshewitt@gmail.com