This changeset fixes up all the IXP2000 issues mentioned in the following message:

http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-August/024156.html

- Remove page table fixups for IXP2400 systems.  There is actually some
  confusion b/w myself and Intel on what mappings really needs this and
  we still need to determine a proper clean way to do this. When we have
  that, we'll add support back in. For now I am still able to boot 
  on IXP2400 systems.

- Replaced __asm__ __volatile__("":::"memory") with barrier()

- Remove inclusion of mach-types.h in ixdp2x01.h. The machine_is_ixdp2x01()
  macro was only being used in one place, so just check for 
  (machine_is_ixdp2401() || machine_is_ixdp2801())
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>