net/mlx5e: Remove unused variable ‘esw’

Fix the following compiler warning:

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:2770:
warning: unused variable ‘esw’ [-Wunused-variable]

Fixes: 1cd3ab86b713 ("net/mlx5e: Introduce mlx5e_flow_esw_attr_init() helper")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>