google/kahlee: Move DRAM clear override to devicetree

Kahlee needs to keep its DRAM contents after a reset. Move this
override out of the OemCustomize.c file to a devicetree register
setting.

Change-Id: I3196cb8b94bec64e8ce59e4285cf8d97f442bd3d
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Signed-off-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-on: https://review.coreboot.org/21858
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/kahlee/OemCustomize.c

@@ -35,6 +35,4 @@ void OemPostParams(AMD_POST_PARAMS *PostParams)
 {
 	PostParams->MemConfig.PlatformMemoryConfiguration =
 				(PSO_ENTRY *)DDR4PlatformMemoryConfiguration;
-	/* disable memory clear for pstore memory storage and boot time */
-	PostParams->MemConfig.EnableMemClr = FALSE;
 }

src/mainboard/google/kahlee/variants/kahlee/devicetree.cb

@@ -18,6 +18,7 @@ chip soc/amd/stoneyridge
 	{
 		{ {0xA0, 0x00} }, // socket 0 - Channel 0, slot 0
 	}"
+	register "dram_clear_on_reset" = "DRAM_CONTENTS_KEEP"
 
 	device cpu_cluster 0 on
 		device lapic 10 on end