net/mlx5: fs, split software and IFC flow destination definitions

Separate flow destinations between software and IFC.
Flow destination type passed by callers was used as the input in
firmware commands and over the years software only types were added
which resulted in mixing between the two.

Create an IFC enum that contains only the flow destinations defined
when talking to the firmware.

Now that there is a proper software only enum for flow destinations
the hardcoded values can be removed as the values are no longer used
in firmware commands.

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