RDMA/mlx5: Remove redundant assignment to ret

Variable 'ret' is set to the rerurn value of function
mlx5_mr_cache_alloc() but this value is never read as it is overwritten
with a new value later on, hence it is a redundant assignment and can be
removed

Clean up the following clang-analyzer warning:

 drivers/infiniband/hw/mlx5/odp.c:421:2: warning: Value stored to 'ret' is never read [clang-analyzer-deadcode.DeadStores]

Fixes: e6fb246c ("RDMA/mlx5: Consolidate MR destruction to mlx5_ib_dereg_mr()")
Link: https://lore.kernel.org/r/1620296001-120406-1-git-send-email-yang.lee@linux.alibaba.comReported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/mlx5/odp.c

@@ -418,7 +418,7 @@ static struct mlx5_ib_mr *implicit_get_child_mr(struct mlx5_ib_mr *imr,
 	if (IS_ERR(odp))
 		return ERR_CAST(odp);
 
-	ret = mr = mlx5_mr_cache_alloc(
+	mr = mlx5_mr_cache_alloc(
 		mr_to_mdev(imr), MLX5_IMR_MTT_CACHE_ENTRY, imr->access_flags);
 	if (IS_ERR(mr)) {
 		ib_umem_odp_release(odp);