multifd: Fill offset and block for reception

We were using the iov directly, but we will need this info on the
following patch.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/multifd.c

@@ -354,6 +354,7 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
         return -1;
     }
 
+    p->pages->block = block;
     for (i = 0; i < p->pages->num; i++) {
         uint64_t offset = be64_to_cpu(packet->offset[i]);
 
@@ -363,6 +364,7 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
                        offset, block->used_length);
             return -1;
         }
+        p->pages->offset[i] = offset;
         p->pages->iov[i].iov_base = block->host + offset;
         p->pages->iov[i].iov_len = page_size;
     }