RDMA/mlx4: Remove an unused variable

'in6' is unused. It is just declared and filled-in.  It can be removed.

This is a left over from commit 5ea8bbfc
("mlx4: Implement IP based gids support for RoCE/SRIOV")

Link: https://lore.kernel.org/r/413dc6e2ea9d85bda1131bbd6a730b7620839eab.1618932283.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>