db-88f6820-gp.h: Load data blobs into lower memory

db-88f6820-gp.h: Load data blobs into lower memory

By default on this platform, u-boot loads data into high memory
in the range of 0x7Fxxxxxx, which generates a data abort when the
kernel tries to read it.  Config the u-boot environment to load
the device tree and initrd image into lower memory to make them
accessible to the kernel.

Signed-off-by: Kevin Smith <kevin.smith@elecsyscorp.com>
Acked-by: Stefan Roese <sr@denx.de>