RDMA/mlx5: Remove duplicate assignment in umr_rereg_pas()

The same value is assigned to 'mr->ibmr.length'. Remove redundant one.

Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
Link: https://lore.kernel.org/r/20220908083058.3993700-1-matsuda-daisuke@fujitsu.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>