ARM: uniphier: set initrd_high environment to skip initrd relocation

ARM: uniphier: set initrd_high environment to skip initrd relocation

The boot_ramdisk_high() checks the environment "initrd_high" and,
if it is set to (ulong)-1, skip the initrd relocation.  This is
useful for faster booting when we know the initrd is already located
within the reach of the kernel.

Change "norboot" to copy images in order to make it work without
depending on the automatic relocation.

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