Add support of AXP803 regulators in the Pine64 device tree.

The phy-supply regulator is also set in EMAC device node, in order to
prevent Ethernet regression by regulator get disabled by regulator
framework.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>