arm64: dts: rockchip: fix Quartz64-A ddr regulator voltage

arm64: dts: rockchip: fix Quartz64-A ddr regulator voltage

The Quartz64 Model A uses a voltage divider to ensure ddr voltage is
within specification from the default regulator configuration.
Adjusting this voltage is detrimental, and currently causes the ddr
voltage to be about 0.8v.

Remove the min and max voltage setpoints for the ddr regulator.

Fixes: 749ae73b388c ("arm64: dts: rockchip: add basic dts for Pine64 Quartz64-A")
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Link: https://lore.kernel.org/r/20220128003809.3291407-2-pgwipeout@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>