rockchip: arm64: rk3399: support DDR3-1866 (i.e. 933MHz clock)

The RK3399 is capable of driving DDR3 at 933MHz (i.e. DDR3-1866),
if the PCB layout permits and appropriate memory timings are used.

This changes the sanity checks to allow a DTS to request DDR3-1866
operation.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

arch/arm/mach-rockchip/rk3399/sdram_rk3399.c

@@ -1087,7 +1087,7 @@ static int sdram_init(struct dram_info *dram,
 
 	debug("Starting SDRAM initialization...\n");
 
-	if ((dramtype == DDR3 && ddr_freq > 800) ||
+	if ((dramtype == DDR3 && ddr_freq > 933) ||
 	    (dramtype == LPDDR3 && ddr_freq > 933) ||
 	    (dramtype == LPDDR4 && ddr_freq > 800)) {
 		debug("SDRAM frequency is to high!");