thinkpad-acpi: adopt input device

Properly init the parent field of the input device.  Thanks to Alan
Jenkins, who noted this problem in a different driver.
Reported-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -8375,6 +8375,7 @@ static int __init thinkpad_acpi_module_init(void)
 						PCI_VENDOR_ID_IBM;
 		tpacpi_inputdev->id.product = TPACPI_HKEY_INPUT_PRODUCT;
 		tpacpi_inputdev->id.version = TPACPI_HKEY_INPUT_VERSION;
+		tpacpi_inputdev->dev.parent = &tpacpi_pdev->dev;
 	}
 	for (i = 0; i < ARRAY_SIZE(ibms_init); i++) {
 		ret = ibm_init(&ibms_init[i]);