The internal.h declares the acpi_create_platform_device(). Without
that include we get a following warning:

drivers/acpi/acpi_platform.c:133:24: warning: symbol 'acpi_create_platform_device' was not declared. Should it be static?
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>