POWERPC: Allow 32-bit hashed pgtable code to support 36-bit physical

This rearranges a bit of code, and adds support for
36-bit physical addressing for configs that use a
hashed page table.  The 36b physical support is not
enabled by default on any config - it must be
explicitly enabled via the config system.

This patch *only* expands the page table code to accomodate
large physical addresses on 32-bit systems and enables the
PHYS_64BIT config option for 86xx.  It does *not*
allow you to boot a board with more than about 3.5GB of
RAM - for that, SWIOTLB support is also required (and
coming soon).

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index 77c7fa0..08266d2 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -711,7 +711,7 @@
 /*
  * Change "struct page" to physical address.
  */
-#define page_to_phys(page)	(page_to_pfn(page) << PAGE_SHIFT)
+#define page_to_phys(page)	((phys_addr_t)page_to_pfn(page) << PAGE_SHIFT)
 
 /* We do NOT want virtual merging, it would put too much pressure on
  * our iommu allocator. Instead, we want drivers to be smart enough