Fix the following bugs:

 - the same ARCH_LOW_ADDRESS_LIMIT statements are duplicated between
   header and relevant source

 - don't ensure ARCH_LOW_ADDRESS_LIMIT perhaps defined by ARCH in
   asm/processor.h is preferred over default in linux/bootmem.h
   completely since the former header isn't included by the latter

Link: http://lkml.kernel.org/r/e046aeaa-e160-6d9e-dc1b-e084c2fd999f@zoho.comSigned-off-by: Nzijun_hu <zijun_hu@htc.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>