RDMA/efa: Support remote read access in MR registration

Enable remote read access for memory regions in order to support RDMA
operations.

Link: https://lore.kernel.org/r/20191121141509.59297-3-galpress@amazon.com


Signed-off-by: Daniel Kranzdorf <dkkranzd@amazon.com>
Reviewed-by: Yossi Leybovich <sleybo@amazon.com>
Signed-off-by: Gal Pressman <galpress@amazon.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>