This board has a X-Powers AXP223 PMIC connected via RSB. Its regulators
provide power to various parts of the SoC and the board.

Also update the regulator supply phandles.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>