memblock: Remove memblock_memory_can_coalesce()

Arch could implement memblock_memor_can_coalesce() to veto merging of
adjacent or overlapping memblock regions; however, no arch did and any
vetoing would trigger WARN_ON().  Memblock regions are supposed to
deal with proper memory anyway.  Remove the unused hook.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1310462166-31469-2-git-send-email-tj@kernel.org


Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>