PNP: ACPI: Fix missing-prototypes in acpi_pnp.c

Fix the following warnings.
drivers/acpi/acpi_pnp.c:382:13: warning: no previous prototype
for ‘acpi_pnp_init’ [-Wmissing-prototypes].
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_pnp.c

@@ -11,6 +11,8 @@
 #include <linux/module.h>
 #include <linux/ctype.h>
 
+#include "internal.h"
+
 static const struct acpi_device_id acpi_pnp_device_ids[] = {
 	/* pata_isapnp */
 	{"PNP0600"},		/* Generic ESDI/IDE/ATA compatible hard disk controller */