powerpc/85xx: support for the TQM8548 module using the big Flash

Some TQM85xx boards could be equipped with up to 1 GiB (NOR) flash
memory and therefore a modified memory map is required and setup by
the board loader. This patch adds an appropriate DTS file.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>