ARM: dts: sun9i: optimus: Fix fixed-regulators

ARM: dts: sun9i: optimus: Fix fixed-regulators

Commit 1848f3f44444 ("ARM: dts: sun9i: Remove GPIO pinctrl nodes to avoid
warnings") was wrong on the optimus, and instead of droping the
pinctrl-names property, it dropped the regulator-name one.

Obviously, that wasn't what was intended. Reinstate regulator-name and drop
pinctrl-names.

Fixes: 1848f3f44444 ("ARM: dts: sun9i: Remove GPIO pinctrl nodes to avoid warnings")
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>