Missed rename of CONFIG_RAM_RK3399_LPDDR4

[David Sebek]

Hi,

I think this line:
https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/ram/rockchip/sdram_rk3399.c#L2957
should be

#if defined(CONFIG_RAM_ROCKCHIP_DEBUG)
instead of
#if defined(CONFIG_RAM_RK3399_LPDDR4)

The condition now evaluates to false on the RockPro64 board in the latest
U-Boot version, which I believe is incorrect.

Thanks,
David Sebek