RDMA: Validate grh_required when handling AVs

Extend the existing grh_required flag to check when AV's are handled that
a GRH is present.

Since we don't want to do query_port during the AV checks for performance
reasons move the flag into the immutable_data.

Signed-off-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>