arm64: dts: allwinner: a64: olinuxino: Fix eMMC supply regulator

A64-OLinuXino-eMMC uses 1.8V for eMMC supply. This is done via a triple
jumper, which sets VCC-PL to either 1.8V or 3.3V. This setting is different
for boards with and without eMMC.

This is not a big issue for DDR52 mode, however the eMMC will not work in
HS200/HS400, since these modes explicitly requires 1.8V.

Fixes: 94f68f3a ("arm64: dts: allwinner: a64: Add A64 OlinuXino board (with eMMC)")
Cc: stable@vger.kernel.org # v5.4
Signed-off-by: Stefan Mavrodiev <stefan@olimex.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>