The option size check is using optval instead of optlen
causing the set option call to fail. Use the correct
field, optlen, for size check.

Fixes: 6a21dfc0 ("RDMA/ucma: Limit possible option size")
Signed-off-by: NChien Tin Tung <chien.tin.tung@intel.com>
Signed-off-by: NShiraz Saleem <shiraz.saleem@intel.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>