arm64: allwinner: a64: pine64: Use dcdc1 regulator for mmc0

Since current tree support AXP803 regulators, replace
fixed regulator with AXP803 dcdc1 regulator.

Tested on pine64.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>