acpi: add export.h to files using THIS_MODULE/EXPORT_SYMBOL

These files were relying on module.h to come in via the path
in an include/acpi header file, but we don't want to have
instances of module.h being included from include/* files
if it can be avoided.  Have the files include export.h instead.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/acpi/acpica/hwxface.c b/drivers/acpi/acpica/hwxface.c
index f75f81a..c2793a8 100644
--- a/drivers/acpi/acpica/hwxface.c
+++ b/drivers/acpi/acpica/hwxface.c
@@ -42,6 +42,7 @@
  * POSSIBILITY OF SUCH DAMAGES.
  */
 
+#include <linux/export.h>
 #include <acpi/acpi.h>
 #include "accommon.h"
 #include "acnamesp.h"