Allocating an MR flow can only be initiated by kernel users, and not from
userspace so a udata parameter is redundant.

Link: https://lore.kernel.org/r/20200706120343.10816-4-galpress@amazon.comSigned-off-by: NGal Pressman <galpress@amazon.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>