ACPI: suppress compiler warning in container.c

This patch fixes following compiler warning when build via make W=1:

drivers/acpi/container.c:183:116: warning: no previous prototype for ‘acpi_container_init’ [-Wmissing-prototypes]
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/container.c

@@ -35,6 +35,8 @@
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 
+#include "internal.h"
+
 #define PREFIX "ACPI: "
 
 #define _COMPONENT			ACPI_CONTAINER_COMPONENT