arm64: dts: meson: odroid-c2: Add missing regulator linked to VDDIO_AO3V3 regulator

As per schematics TFLASH_VDD, TF_IO, VCC3V3 fixed regulator output which
is supplied by VDDIO_AO3V3.

While here, move the comment name with the signal name in the
schematics above the gpio property to make it consistent with other
regulators.

Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>