ram: rk3399: Don't disable dfi dram clk for lpddr4, rank 1

ram: rk3399: Don't disable dfi dram clk for lpddr4, rank 1

The hardware for LPDDR4 with
- CLK0P/N connect to lower 16-bits
- CLK1P/N connect to higher 16-bits

and usually dfi dram clk is configured via CLK1P/N, so
disabling dfi dram clk will disable the CLK1P/N as well.

So, add patch to not to disable dfi dram clk for lpddr4,
with rank 1.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: YouMin Chen <cym@rock-chips.com>
Reviewed-by: Kever Yang <Kever.yang@rock-chips.com>