ARM: dts: sunxi: bananapi-m2-plus-v1.2: Add regulator supply to all CPU cores

The device tree currently only assigns the a supply for the first CPU
core, when in reality the regulator supply is shared by all four cores.
This might cause an issue if the implementation does not realize the
sharing of the supply.

Assign the same regulator supply to the remaining CPU cores to address
this.

Fixes: 6eeb4180 ("ARM: dts: sunxi: h3-h5: Add Bananapi M2+ v1.2 device trees")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20200717160053.31191-3-wens@kernel.org