powerpc/mpc85xx: socrates: add initrd_high default environment variable

we need to set initrd_high to get fitimage booting.

Without, U-Boot drops when booting fitimage:

ERROR: Failed to allocate 0x59a0b6 bytes below 0x800000.
ramdisk - allocation error
bootm - boot application image from memory

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/include/configs/socrates.h b/include/configs/socrates.h
index 67ff370..ed10031 100644
--- a/include/configs/socrates.h
+++ b/include/configs/socrates.h
@@ -118,6 +118,7 @@
 #define	CFG_EXTRA_ENV_SETTINGS					\
 	"netdev=eth0\0"							\
 	"consdev=ttyS0\0"						\
+	"initrd_high=0x03000000\0"					\
 	"uboot_file=/home/tftp/syscon3/u-boot.bin\0"			\
 	"bootfile=/home/tftp/syscon3/uImage\0"				\
 	"fdt_file=/home/tftp/syscon3/socrates.dtb\0"			\