ARM: uniphier: fix DRAM size of LD21 SoC package

The channel 0 DRAM size of LD21 is half of that of LD20.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/boards.c b/arch/arm/mach-uniphier/boards.c
index 20093d8..e063555 100644
--- a/arch/arm/mach-uniphier/boards.c
+++ b/arch/arm/mach-uniphier/boards.c
@@ -209,7 +209,7 @@
 	.dram_nr_ch = 2,
 	.dram_ch[0] = {
 		.base = 0x80000000,
-		.size = 0x40000000,
+		.size = 0x20000000,
 		.width = 32,
 	},
 	.dram_ch[1] = {