ACPI: move private declarations to internal.h

A number of things that shouldn't be exposed outside the ACPI core
were declared in include/acpi/acpi_drivers.h, where anybody can
see them.  This patch moves those declarations to a new "internal.h"
inside drivers/acpi.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index c54d7b6..2f04cd11 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -11,6 +11,8 @@
 
 #include <acpi/acpi_drivers.h>
 
+#include "internal.h"
+
 #define _COMPONENT		ACPI_BUS_COMPONENT
 ACPI_MODULE_NAME("scan");
 #define STRUCT_TO_INT(s)	(*((int*)&s))