arm64: dts: rockchip: add micro SD card regulator to rockpro64

This patch adds the RockPro64's micro SD card regulator to the
RockPro64 dtsi. The regulator is present on all revisions of the
device.
Previously the regular was missing, resulting in unreliable boot
behaviour when booting from SD card.

Signed-off-by: Tobias Schramm <t.schramm@manjaro.org>
Link: https://lore.kernel.org/r/20200416145534.1263575-1-t.schramm@manjaro.org


Signed-off-by: Heiko Stuebner <heiko@sntech.de>