The change is currently needed to be able to remove the board
configuration scripting from the top level Makefile and replace it by
a simple, table driven script.

Moving this configuration setting into the "CONFIG_*" name space is
also desirable because it is needed if we ever should move forward to
a Kconfig driven configuration system.

Signed-off-by: Wolfgang Denk <wd@denx.de>

ARM memory layout fixes: the abort-stack is now set up in the
correct RAM area, and the BSS is zeroed out as it should be.

Furthermore, the magic variables 'armboot_end' and 'armboot_end_data'
of the linker scripts are replaced by '__bss_start' and '_end',
resp., which is a further step to eliminate unnecessary differences
between the implementation of the CPU architectures.

  Move most of the timer interrupt related PPC code to ppc_lib/interrupts.c

* Patch by Anders Larsen, 17 Sep 2003:
  Bring ARM memory layout in sync with the documentation:
  stack and malloc-heap are now located _below_ the U-Boot code