configs: OrangePi PC2: Update defaults

configs: OrangePi PC2: Update defaults

OrangePi PC2 board has DRAM with ODT, so enable it.
H5 SoC is also connected to voltage regulator. It's default value is
reasonable at reset, but might be too low when rebooting with a lower
voltage programmed. In order to avoid instability, enable driver for it
and set it to appropriate voltage.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
[Andre: remove original ZQ value change, adjust commit message]
Signed-off-by: Andre Przywara <andre.przywara@arm.com>