powerpc/mpc8272ads: fix device tree for 8 MB flash size

The current device tree for the MPC8272ADS assumes a mapping of 32 MB
of NOR flash at 0xFE00.0000, while there are actually only 8 MB on
the boards, mapped at 0xFF80.0000. When booting an uImage with such a
device tree, the kernel crashes because 0xFE00.0000 is not mapped.

Also introduce aliases for serial[01] and ethernet[01].

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>