ACPI / PNP: add soc_button_array device ID to PNP IDs list

The soc_button_array PNP driver was introduced in 3.15.
But in commit eec15edbb0 (ACPI / PNP: use device ID list for
PNPACPI device enumeration), when reworking the PNPACPI device
enumeration, we missed the soc_button_array device ID.

This results in a regression in 3.16-rc1 that soc_button_array
pnp device fails to be enumerated.

Fix the problem by adding soc_button_array device ID into the
acpi_pnp scan handler's ID list.

Fixes: eec15edbb0 (ACPI / PNP: use device ID list for PNPACPI device enumeration)
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_pnp.c

@@ -14,6 +14,8 @@
 #include <linux/module.h>
 
 static const struct acpi_device_id acpi_pnp_device_ids[] = {
+	/* soc_button_array */
+	{"PNP0C40"},
 	/* pata_isapnp */
 	{"PNP0600"},		/* Generic ESDI/IDE/ATA compatible hard disk controller */
 	/* floppy */