Initial drop action support missed that drop action can be added to egress
flow tables as well. Add the missing support.

This requires making sure that dest_type isn't set to PORT which in turn
exposes a possibility of passing dst while indicating number of dsts as
zero. Explicitly check for number of dsts and pass the appropriate
pointer.

Fixes: f29de9ee ("RDMA/mlx5: Add support for drop action in DV steering")
Link: https://lore.kernel.org/r/20210318135123.680759-1-leon@kernel.orgReviewed-by: Mark Bloch <markb@nvidia.com>
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>