ARM: rmobile: Point load address to more sane area on Gen2

ARM: rmobile: Point load address to more sane area on Gen2

Point the $loadaddr variable and default load address to a more sane
area, 256 MiB from the start of RAM. While it is convenient to use
uImage without copying, which is why the previous load address was
set the way it was, uImage is now legacy. This behavior could still
be easily retained by "setenv loadaddr 0x40007fc0" . The new setup
allows us to use for example modern fitImage with kernel_noload, so
use this as a new preferred default.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>