toshiba_acpi: return on a fail path

Return from bt_rfkill_poll() when hci_get_radio_state() fails.

value is invalid in that case and should not be assigned to the rfkill
state.

This also fixes a double unlock bug.

Signed-off-by: Jiri Slaby <[e-mail]>
Cc: John W. Linville <[e-mail]>
Cc: Johannes Berg <[e-mail]>
Cc: Henrique de Moraes Holschuh <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>

drivers/platform/x86/toshiba_acpi.c

···
 	if (hci_result != HCI_SUCCESS) {
 		/* Can't do anything useful */
 		mutex_unlock(&dev->mutex);
+		return;
 	}
 
 	new_rfk_state = value;