virtiofsd: Get rid of unreachable code in read

pvreadv() can return following.

- error
- 0 in case of EOF
- short read

We seem to handle all the cases already. We are retrying read in case
of short read. So another check for short read seems like dead code.
Get rid of it.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210518213538.693422-3-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

tools/virtiofsd/fuse_virtio.c

@@ -446,11 +446,6 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
                      in_sg_left);
             break;
         }
-        if (ret != len) {
-            fuse_log(FUSE_LOG_DEBUG, "%s: ret!=len\n", __func__);
-            ret = EIO;
-            goto err;
-        }
         in_sg_left -= ret;
         len -= ret;
     } while (in_sg_left);