ARM: Add support for S3C6400 based SMDK6400 board

SMDK6400 can only boot U-Boot from NAND-flash. This patch adds a nand_spl
driver for it too. The board can also boot from the NOR flash, but due to
hardware limitations it can only address 64KiB on it, which is not enough
for U-Boot. Based on the original sources by Samsung for U-Boot 1.1.6.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
diff --git a/MAKEALL b/MAKEALL
index e382947..4225df3 100755
--- a/MAKEALL
+++ b/MAKEALL
@@ -519,6 +519,7 @@
 	imx31_litekit	\
 	imx31_phycore	\
 	mx31ads		\
+	smdk6400	\
 "
 
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