net/mlx5e: Remove redundant newline in NL_SET_ERR_MSG_MOD

Fix the following coccicheck warnings:

drivers/net/ethernet/mellanox/mlx5/core/devlink.c:145:29-66: WARNING
avoid newline at end of message in NL_SET_ERR_MSG_MOD
drivers/net/ethernet/mellanox/mlx5/core/devlink.c:140:29-77: WARNING
avoid newline at end of message in NL_SET_ERR_MSG_MOD

Signed-off-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>