RDMA: Remove redundant = {} for udata req structs

RDMA: Remove redundant = {} for udata req structs

Now that all of the udata request structs are loaded with the helpers
the callers should not pre-zero them. The helpers all guarantee that
the entire struct is filled with something.

Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>