all arm boards except a few use the same cpu linker script
so move it to cpu/$(CPU)

that could be overwrite in following order
SOC
BOARD
via the corresponding config.mk

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

Modifications are based on the linux kernel approach and
support two use cases:

  1) Add O= to the make command line
  'make O=/tmp/build all'

  2) Set environement variable BUILD_DIR to point to the desired location
  'export BUILD_DIR=/tmp/build'
  'make'

The second approach can also be used with a MAKEALL script
'export BUILD_DIR=/tmp/build'
'./MAKEALL'

Command line 'O=' setting overrides BUILD_DIR environent variable.

When none of the above methods is used the local build is performed and
the object files are placed in the source directory.

  Added ARM Integrator AP, CP and Versatile PB926EJ-S Reference
  Platform support.

* Patch by Masami Komiya, 08 Mar 2004:
  Don't overwrite server IP address or boot file name
  when the boot server does not return values

* Patch by listmember@orkun.us, 5 Mar 2004:
  Removed compile time restriction on CFG_I2C_SPEED for DS1338 RTC