ARM: uniphier: define CONFIG_SYS_BOOTMAPSZ

U-Boot relocates the device tree and the initramdisk to the tail
of the memory region before booting the kernel.

Some UniPhier boards are equipped with a large amount of memory.
For those boards, the device tree and the initramdisk are placed out
of the the kernel causing a kernel panic.

Add CONFIG_SYS_BOOTMAPSZ to prevent them from going too high.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

include/configs/uniphier.h

@@ -226,6 +226,8 @@
 		"nand write $loadaddr 0x00010000 0x000f0000\0"	\
 	LINUXBOOT_ENV_SETTINGS
 
+#define CONFIG_SYS_BOOTMAPSZ			0x20000000
+
 /* Open Firmware flat tree */
 #define CONFIG_OF_LIBFDT