migration/rdma: Check qemu_rdma_init_one_block

Actually it can't fail at the moment, but Coverity moans that
it's the only place it's not checked, and it's an easy check.

Reported-by: Coverity (CID 1399413)
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

migration/rdma.c

@@ -641,10 +641,14 @@ static int qemu_rdma_init_one_block(RAMBlock *rb, void *opaque)
 static int qemu_rdma_init_ram_blocks(RDMAContext *rdma)
 {
     RDMALocalBlocks *local = &rdma->local_ram_blocks;
+    int ret;
 
     assert(rdma->blockmap == NULL);
     memset(local, 0, sizeof *local);
-    foreach_not_ignored_block(qemu_rdma_init_one_block, rdma);
+    ret = foreach_not_ignored_block(qemu_rdma_init_one_block, rdma);
+    if (ret) {
+        return ret;
+    }
     trace_qemu_rdma_init_ram_blocks(local->nb_blocks);
     rdma->dest_blocks = g_new0(RDMADestBlock,
                                rdma->local_ram_blocks.nb_blocks);