IB: Support ib_flow creation in drivers

This patch considers the case that ib_flow is created by some device
driver with its specific parameters using the KABI infrastructure.

In that case both QP and ib_uflow_resources might not be applicable.
Downstream patches from this series use the above functionality.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>