net/mlx5e: Fix usage of rcu-protected pointer

In mlx5e_configure_flower() flow pointer is protected by rcu read lock.
However, after cited commit the pointer is being used outside of rcu read
block. Extend the block to protect all pointer accesses.

Fixes: 553f9328

 ("net/mlx5e: Support tc block sharing for representors")
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>