net/mlx5: fs, refactor software deletion rule

When deleting a rule make sure that for every type dests_size is
decreased only once and no other logic is executed.

Without this dests_size might be decreased twice when dests_size == 1
so the if for that type won't be entered and if action has
MLX5_FLOW_CONTEXT_ACTION_FWD_DEST set dests_size will be decreased again.

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>