regulator: axp20x: Drop AXP221 DC1SW and DC5LDO regulator supplies from bindings

The DC1SW and DC5LDO regulators in the AXP221 are internally chained
to DCDC1 and DCDC5, hence the names. The original bindings used the
parent regulator names for the supply regulator property. This causes
some confusion when we actually use it in the dts:

	axp221 {
		/* self supplying? */
		dcdc1-supply = <&dcdc1>;
		dcdc5-supply = <&dcdc5>;

		dcdc1: dcdc1 {
			...
		};

		dcdc5: dcdc5 {
			...
		};
	};

Since they are internally connected within the PMIC, their relationships
should not be visible in the device tree.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Mark Brown <broonie@kernel.org>