ARM: dts: sun8i: nanopi-duo2: Fix regulator GPIO reference

ARM: dts: sun8i: nanopi-duo2: Fix regulator GPIO reference

The property named in the schema is 'enable-gpios', not 'enable-gpio'.
This makes no difference at runtime, because the regulator is marked as
always-on, but it breaks validation.

Fixes: 4701fc6e5dd9 ("ARM: dts: sun8i: add FriendlyARM NanoPi Duo2")
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20221231225854.16320-2-samuel@sholland.org
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>