RDMA/cm: Remove CM message structs

All accesses now use the new IBA acessor scheme, so delete the structs
entirely and generate the structures from the schema file.

Link: https://lore.kernel.org/r/20200116170037.30109-8-jgg@ziepe.ca
Tested-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>