migration: update index field when delete or qsort RDMALocalBlock

migration: update index field when delete or qsort RDMALocalBlock

rdma_delete_block function deletes RDMALocalBlock base on index field,
but not update the index field. So when next time invoke rdma_delete_block,
it will not work correctly.

If start and cancel migration repeatedly, some RDMALocalBlock not invoke
ibv_dereg_mr to decrease kernel mm_struct vmpin. When vmpin is large than
max locked memory limitation, ibv_reg_mr will failed, and migration can not
start successfully again.

Signed-off-by: Lidong Chen <[email protected]>
Reviewed-by: Dr. David Alan Gilbert <[email protected]>
Message-Id: <1525618499[email protected]>
Signed-off-by: Juan Quintela <[email protected]>
Signed-off-by: Lidong Chen <[email protected]>