arm64: dts: meson-sm1-odroid-hc4: disable unused USB PHY0

As described in the HC4 schematics, only the USB port B is used,
port A is left unconnected. Thus disable PHY0 and remove it from PHYs list.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20210607065435.577334-5-narmstrong@baylibre.com