powerpc: numa.c: always trim to lmb_end_of_DRAM

[Milton Miller <miltonm@bga.com>]

numa_enforce_memory_limit trys to be smart and only trim the memory it
finds to lmb_end_of_DRAM when a memory limit is set.   However, the
early boot code may also limit memory when iommu=off is specified.  When
this happens, the page allocator is told of pages not in the linear mapping
and gets a fatal DSI.

Signed-off-by: Milton Miller <miltonm@bga.com>
--
Previously this patch tried to check if iommu=off was specified, but it was
requested that the check just be removed.

http://patchwork.ozlabs.org/linuxppc/patch?id=11774

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index cf4bffb..590406c 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -472,12 +472,10 @@ static unsigned long __init numa_enforce_memory_limit(unsigned long start,
 	/*
 	 * We use lmb_end_of_DRAM() in here instead of memory_limit because
 	 * we've already adjusted it for the limit and it takes care of
-	 * having memory holes below the limit.
+	 * having memory holes below the limit.  Also, in the case of
+	 * iommu_is_off, memory_limit is not set but is implicitly enforced.
 	 */
 
-	if (! memory_limit)
-		return size;
-
 	if (start + size <= lmb_end_of_DRAM())
 		return size;