RDMA/mlx5: Group all create QP parameters to simplify in-kernel interfaces

The amount of parameters passed in and out between internal mlx5
create QP functions is too large to easily follow the flow. Change
it by grouping all create QP parameter into one structure.

Link: https://lore.kernel.org/r/20200427154636.381474-31-leon@kernel.org
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>