net/mlx5: Typo fix in del_sw_hw_rule

Expression terminated with "," instead of ";", resulted in
set_fte getting bad value for modify_enable_mask field.

Fixes: bd5251db ("net/mlx5_core: Introduce flow steering destination of type counter")
Signed-off-by: Yuval Avnery <yuvalav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>