ARM: dts: sun6i: hummingbird: Drop AXP221 DC1SW and DC5LDO supplies

"dcdc1-supply" and "dcdc5-supply" have been dropped, as they are
internally connected and should not be represented in the device
tree.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>