RDMA/rdmavt: Remove FMR memory registration

Use FRWR method to register memory by default and remove the ancient and
unsafe FMR method.

Link: https://lore.kernel.org/r/10-v3-f58e6669d5d3+2cf-fmr_removal_jgg@mellanox.com


Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Tested-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>