RDMA/core: Do not erase the type of ib_srq.uobject

This is a struct ib_usrq_object pointer, instead of using container_of()
all over the place just store it with its actual type.

Link: https://lore.kernel.org/r/1578504126-9400-9-git-send-email-yishaih@mellanox.com


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