hfi1/user_exp_rcv/invalid: Remove function

user_exp_rcv_invalid is only used together with the mmu cache
(its purpose is the delayed freeing of tids that were invalidated in cache)

Since we do not use that cache, the function can go

kernel/file_ops.c

@@ -516,18 +516,9 @@ long hfi1_file_ioctl(void *private_data, unsigned int cmd,
 
 	case HFI1_IOCTL_TID_INVAL_READ:
 		kprintf("%s: HFI1_IOCTL_TID_INVAL_READ \n", __FUNCTION__);
-		if (copy_from_user(&tinfo,
-				   (struct hfi11_tid_info __user *)arg,
-				   sizeof(tinfo)))
-			return -EFAULT;
-
-		ret = hfi1_user_exp_rcv_invalid(fd, &tinfo);
-		if (ret)
-			break;
-		addr = arg + offsetof(struct hfi1_tid_info, tidcnt);
-		if (copy_to_user((void __user *)addr, &tinfo.tidcnt,
-				 sizeof(tinfo.tidcnt)))
-			ret = -EFAULT;
+		/* This function is only invovled with the tid mmu caching.
+		 * It is a no-op for us. */
+		ret = 0;
 		break;
 
 	case HFI1_IOCTL_RECV_CTRL: