ACPICA: Add post-order callback to acpi_walk_namespace

The existing interface only has a pre-order callback. This change
adds an additional parameter for a post-order callback which will
be more useful for bus scans. ACPICA BZ 779.

Also update the external calls to acpi_walk_namespace.

http://www.acpica.org/bugzilla/show_bug.cgi?id=779

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

include/acpi/acpixf.h

@@ -154,7 +154,8 @@ acpi_status
 acpi_walk_namespace(acpi_object_type type,
 		    acpi_handle start_object,
 		    u32 max_depth,
-		    acpi_walk_callback user_function,
+		    acpi_walk_callback pre_order_visit,
+		    acpi_walk_callback post_order_visit,
 		    void *context, void **return_value);
 
 acpi_status