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>
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index baef28c..75b147f 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -820,7 +820,7 @@
 
 	/* Find and register all query methods */
 	acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
-			    acpi_ec_register_query_methods, ec, NULL);
+			    acpi_ec_register_query_methods, NULL, ec, NULL);
 
 	if (!first_ec)
 		first_ec = ec;