ARM: uniphier: add default bootm_low to fix FIT boot

Commit 25d4eb8091f4 ("ARM: uniphier: add bootm_low environment")
missed to add "bootm_low" for FIT boot.  Set "bootm_low" to the
DRAM base address.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/include/configs/uniphier.h b/include/configs/uniphier.h
index ec4fd67..00c27f1 100644
--- a/include/configs/uniphier.h
+++ b/include/configs/uniphier.h
@@ -223,6 +223,7 @@
 	"netdev=eth0\0"						\
 	"verify=n\0"						\
 	"nor_base=0x42000000\0"					\
+	"bootm_low=0x80000000\0"				\
 	"nandupdate=nand erase 0 0x00100000 &&"			\
 		"tftpboot u-boot-spl-dtb.bin &&"		\
 		"nand write $loadaddr 0 0x00010000 &&"		\