net/mlx5e: Add tc flower tracepoints

Implemented following tracepoints:
1. Configure flower (mlx5e_configure_flower)
2. Delete flower (mlx5e_delete_flower)
3. Stats flower (mlx5e_stats_flower)

Usage example:
 ># cd /sys/kernel/debug/tracing
 ># echo mlx5:mlx5e_configure_flower >> set_event
 ># cat trace
    ...
    tc-6535  [019] ...1  2672.404466: mlx5e_configure_flower: cookie=0000000067874a55 actions= REDIRECT

Added corresponding documentation in
    Documentation/networking/device-driver/mellanox/mlx5.rst

Signed-off-by: Dmytro Linkin <dmitrolin@mellanox.com>
Reviewed-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>