pinephone-pro: Fix I/O port voltage (GPIO3D4A is 1.8V)

This fixes access to camera sensor over I2C during probe time in
the kernel. (Kernel will fix I/0 port voltage by itself, but the
timing depends on probe order of the drivers, so the fix can
come after the camera sensor driver already failed to probe.)

Signed-off-by: Ondrej Jirman <megi@xff.cz>
Cc: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Peter Robinson <pbrobinson@gmail.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>